241 lines
8.4 KiB
Diff
241 lines
8.4 KiB
Diff
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From 8f8027c5f935bf02bdc8806c109ddbb0e402283c Mon Sep 17 00:00:00 2001
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From: Al Stone <ahs3@redhat.com>
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Date: Wed, 16 May 2018 16:01:41 -0600
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Subject: [PATCH] mailbox: PCC: erroneous error message when parsing ACPI PCCT
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There have been multiple reports of the following error message:
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[ 0.068293] Error parsing PCC subspaces from PCCT
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This error message is not correct. In multiple cases examined, the PCCT
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(Platform Communications Channel Table) concerned is actually properly
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constructed; the problem is that acpi_pcc_probe() which reads the PCCT
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is making the assumption that the only valid PCCT is one that contains
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subtables of one of two types: ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE or
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ACPI_PCCT_TYPE_HW_REDUCED_TYPE2. The number of subtables of these
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types are counted and as long as there is at least one of the desired
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types, the acpi_pcc_probe() succeeds. When no subtables of these types
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are found, regardless of whether or not any other subtable types are
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present, the error mentioned above is reported.
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In the cases reported to me personally, the PCCT contains exactly one
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subtable of type ACPI_PCCT_TYPE_GENERIC_SUBSPACE. The function
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acpi_pcc_probe() does not count it as a valid subtable, so believes
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there to be no valid subtables, and hence outputs the error message.
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An example of the PCCT being reported as erroneous yet perfectly fine
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is the following:
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Signature : "PCCT"
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Table Length : 0000006E
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Revision : 05
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Checksum : A9
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Oem ID : "XXXXXX"
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Oem Table ID : "XXXXX "
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Oem Revision : 00002280
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Asl Compiler ID : "XXXX"
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Asl Compiler Revision : 00000002
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Flags (decoded below) : 00000001
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Platform : 1
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Reserved : 0000000000000000
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Subtable Type : 00 [Generic Communications Subspace]
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Length : 3E
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Reserved : 000000000000
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Base Address : 00000000DCE43018
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Address Length : 0000000000001000
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Doorbell Register : [Generic Address Structure]
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Space ID : 01 [SystemIO]
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Bit Width : 08
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Bit Offset : 00
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Encoded Access Width : 01 [Byte Access:8]
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Address : 0000000000001842
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Preserve Mask : 00000000000000FD
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Write Mask : 0000000000000002
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Command Latency : 00001388
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Maximum Access Rate : 00000000
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Minimum Turnaround Time : 0000
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To fix this, we count up all of the possible subtable types for the
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PCCT, and only report an error when there are none (which could mean
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either no subtables, or no valid subtables), or there are too many.
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We also change the logic so that if there is a valid subtable, we
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do try to initialize it per the PCCT subtable contents. This is a
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change in functionality; previously, the probe would have returned
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right after the error message and would not have tried to use any
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other subtable definition.
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Tested on my personal laptop which showed the error previously; the
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error message no longer appears and the laptop appears to operate
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normally.
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Signed-off-by: Al Stone <ahs3@redhat.com>
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Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>
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Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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---
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drivers/mailbox/pcc.c | 81 ++++++++++++++++++++++++---------------------------
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1 file changed, 38 insertions(+), 43 deletions(-)
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diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
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index 3ef7f036ceea..fc3c237daef2 100644
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--- a/drivers/mailbox/pcc.c
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+++ b/drivers/mailbox/pcc.c
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@@ -373,33 +373,24 @@ static const struct mbox_chan_ops pcc_chan_ops = {
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};
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/**
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- * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
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- * entries. There should be one entry per PCC client.
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+ * parse_pcc_subspaces -- Count PCC subspaces defined
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* @header: Pointer to the ACPI subtable header under the PCCT.
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* @end: End of subtable entry.
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*
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- * Return: 0 for Success, else errno.
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+ * Return: If we find a PCC subspace entry of a valid type, return 0.
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+ * Otherwise, return -EINVAL.
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*
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* This gets called for each entry in the PCC table.
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*/
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static int parse_pcc_subspace(struct acpi_subtable_header *header,
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const unsigned long end)
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{
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- struct acpi_pcct_hw_reduced *pcct_ss;
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-
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- if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
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- pcct_ss = (struct acpi_pcct_hw_reduced *) header;
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+ struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
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- if ((pcct_ss->header.type !=
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- ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE)
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- && (pcct_ss->header.type !=
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- ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)) {
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- pr_err("Incorrect PCC Subspace type detected\n");
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- return -EINVAL;
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- }
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- }
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+ if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
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+ return 0;
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- return 0;
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+ return -EINVAL;
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}
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/**
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@@ -449,8 +440,8 @@ static int __init acpi_pcc_probe(void)
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struct acpi_table_header *pcct_tbl;
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struct acpi_subtable_header *pcct_entry;
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struct acpi_table_pcct *acpi_pcct_tbl;
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+ struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
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int count, i, rc;
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- int sum = 0;
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acpi_status status = AE_OK;
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/* Search for PCCT */
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@@ -459,43 +450,41 @@ static int __init acpi_pcc_probe(void)
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if (ACPI_FAILURE(status) || !pcct_tbl)
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return -ENODEV;
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- count = acpi_table_parse_entries(ACPI_SIG_PCCT,
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- sizeof(struct acpi_table_pcct),
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- ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
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- parse_pcc_subspace, MAX_PCC_SUBSPACES);
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- sum += (count > 0) ? count : 0;
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-
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- count = acpi_table_parse_entries(ACPI_SIG_PCCT,
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- sizeof(struct acpi_table_pcct),
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- ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2,
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- parse_pcc_subspace, MAX_PCC_SUBSPACES);
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- sum += (count > 0) ? count : 0;
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+ /* Set up the subtable handlers */
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+ for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
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+ i < ACPI_PCCT_TYPE_RESERVED; i++) {
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+ proc[i].id = i;
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+ proc[i].count = 0;
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+ proc[i].handler = parse_pcc_subspace;
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+ }
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- if (sum == 0 || sum >= MAX_PCC_SUBSPACES) {
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- pr_err("Error parsing PCC subspaces from PCCT\n");
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+ count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
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+ sizeof(struct acpi_table_pcct), proc,
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+ ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
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+ if (count == 0 || count > MAX_PCC_SUBSPACES) {
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+ pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
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return -EINVAL;
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}
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- pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
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- sum, GFP_KERNEL);
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+ pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) * count, GFP_KERNEL);
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if (!pcc_mbox_channels) {
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pr_err("Could not allocate space for PCC mbox channels\n");
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return -ENOMEM;
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}
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- pcc_doorbell_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
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+ pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
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if (!pcc_doorbell_vaddr) {
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rc = -ENOMEM;
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goto err_free_mbox;
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}
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- pcc_doorbell_ack_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
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+ pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
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if (!pcc_doorbell_ack_vaddr) {
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rc = -ENOMEM;
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goto err_free_db_vaddr;
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}
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- pcc_doorbell_irq = kcalloc(sum, sizeof(int), GFP_KERNEL);
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+ pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL);
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if (!pcc_doorbell_irq) {
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rc = -ENOMEM;
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goto err_free_db_ack_vaddr;
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@@ -509,18 +498,24 @@ static int __init acpi_pcc_probe(void)
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if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
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pcc_mbox_ctrl.txdone_irq = true;
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- for (i = 0; i < sum; i++) {
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+ for (i = 0; i < count; i++) {
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struct acpi_generic_address *db_reg;
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- struct acpi_pcct_hw_reduced *pcct_ss;
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+ struct acpi_pcct_subspace *pcct_ss;
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pcc_mbox_channels[i].con_priv = pcct_entry;
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- pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
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+ if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
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+ pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
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+ struct acpi_pcct_hw_reduced *pcct_hrss;
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+
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+ pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry;
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- if (pcc_mbox_ctrl.txdone_irq) {
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- rc = pcc_parse_subspace_irq(i, pcct_ss);
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- if (rc < 0)
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- goto err;
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+ if (pcc_mbox_ctrl.txdone_irq) {
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+ rc = pcc_parse_subspace_irq(i, pcct_hrss);
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+ if (rc < 0)
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+ goto err;
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+ }
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}
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+ pcct_ss = (struct acpi_pcct_subspace *) pcct_entry;
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/* If doorbell is in system memory cache the virt address */
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db_reg = &pcct_ss->doorbell_register;
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@@ -531,7 +526,7 @@ static int __init acpi_pcc_probe(void)
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((unsigned long) pcct_entry + pcct_entry->length);
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}
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- pcc_mbox_ctrl.num_chans = sum;
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+ pcc_mbox_ctrl.num_chans = count;
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pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
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--
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2.14.3
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