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Date: Mon, 30 Apr 2018 17:39:05 -0600
From: Al Stone <ahs3@...hat.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Jassi Brar <jassisinghbrar@...il.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v2 3/3] mailbox: ACPI: erroneous error message when
parsing the ACPI PCCT
On 04/27/2018 05:16 AM, Rafael J. Wysocki wrote:
> On Tue, Apr 24, 2018 at 9:35 PM, Al Stone <ahs3@...hat.com> wrote:
>> There have been multiple reports of the following error message:
>>
>> [ 0.068293] Error parsing PCC subspaces from PCCT
>>
>
> [cut]
>
>>
>> Tested on my personal laptop which showed the error previously; the
>> error message no longer appears and the laptop appears to operate
>> normally.
>>
>> Signed-off-by: Al Stone <ahs3@...hat.com>
>> Cc: Jassi Brar <jassisinghbrar@...il.com>
>> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
>> Cc: Len Brown <lenb@...nel.org>
>> ---
>> drivers/mailbox/pcc.c | 99 +++++++++++++++++++++++++++++++++++++--------------
>> 1 file changed, 73 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
>> index 3ef7f036ceea..cc77a2f1694f 100644
>> --- a/drivers/mailbox/pcc.c
>> +++ b/drivers/mailbox/pcc.c
>> @@ -372,6 +372,35 @@ static const struct mbox_chan_ops pcc_chan_ops = {
>> .send_data = pcc_send_data,
>> };
>>
>> +/*
>> + *
>> + * count_pcc_subspaces -- Count the PCC subspaces that are not used in
>> + * reduced hardware systems.
>
> One line here, please.
Ack.
>> + * @header: Pointer to the ACPI subtable header under the PCCT.
>> + * @end: End of subtable entry.
>> + *
>> + * Return: 0 for Success, else errno.
>
> The only errno returned appears to be -EINVAL, so maybe say when that
> is returned and then "or 0 otherwise".
Okay.
>> + *
>> + * This gets called for each entry in the PCC table.
>> + */
>> +static int count_pcc_subspaces(struct acpi_subtable_header *header,
>> + const unsigned long end)
>> +{
>> + struct acpi_pcct_subspace *pcct_ss =
>> + (struct acpi_pcct_subspace *) header;
>
> This can be one line (ignore warnings from checkpatch about that).
Okay. That's always a bit of a judgment call with checkpatch.
>> +
>> + if ((pcct_ss->header.type <= ACPI_PCCT_TYPE_RESERVED) &&
>> + (pcct_ss->header.type != ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) &&
>> + (pcct_ss->header.type !=
>> + ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)) {
>
> This can be one line too.
Okay.
>> + pr_warn("PCCT count: useful subtype = %d\n",
>> + pcct_ss->header.type);
>
> Why pr_warn()?
>
>> + return 0;
>> + }
>> + pr_warn("PCCT count: unwanted subtype = %d\n", pcct_ss->header.type);
>> + return -EINVAL;
>> +}
>> +
Oh, bugger. I inadvertently left some debug noise in here. Both of the above
pr_warn() calls should go away since they don't actually provide any value.
>> /**
>> * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
>> * entries. There should be one entry per PCC client.
>> @@ -395,10 +424,14 @@ static int parse_pcc_subspace(struct acpi_subtable_header *header,
>> && (pcct_ss->header.type !=
>> ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)) {
>> pr_err("Incorrect PCC Subspace type detected\n");
>> + pr_warn("PCCT parse: unwanted subtype = %d\n",
>> + pcct_ss->header.type);
>
> Maybe merge the two messages?
Yup, or remove the pr_warn(); that's really just extra debug info I had put in
to check results.
>
>> return -EINVAL;
>> }
>> }
>>
>> + pcct_ss = (struct acpi_pcct_hw_reduced *) header;
>> + pr_warn("PCCT parse: useful subtype = %d\n", pcct_ss->header.type);
...and same here -- the pr_warn() is extraneous, really.
>> return 0;
>> }
>>
>> @@ -449,8 +482,8 @@ static int __init acpi_pcc_probe(void)
>> struct acpi_table_header *pcct_tbl;
>> struct acpi_subtable_header *pcct_entry;
>> struct acpi_table_pcct *acpi_pcct_tbl;
>> + struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
>> int count, i, rc;
>> - int sum = 0;
>> acpi_status status = AE_OK;
>>
>> /* Search for PCCT */
>> @@ -459,43 +492,50 @@ static int __init acpi_pcc_probe(void)
>> if (ACPI_FAILURE(status) || !pcct_tbl)
>> return -ENODEV;
>>
>> - count = acpi_table_parse_entries(ACPI_SIG_PCCT,
>> - sizeof(struct acpi_table_pcct),
>> - ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
>> - parse_pcc_subspace, MAX_PCC_SUBSPACES);
>> - sum += (count > 0) ? count : 0;
>> -
>> - count = acpi_table_parse_entries(ACPI_SIG_PCCT,
>> - sizeof(struct acpi_table_pcct),
>> - ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2,
>> - parse_pcc_subspace, MAX_PCC_SUBSPACES);
>> - sum += (count > 0) ? count : 0;
>> + /* Set up the subtable handlers */
>> + for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
>> + i < ACPI_PCCT_TYPE_RESERVED;
>
> I would append the line below to this one.
Okay.
>> + i++) {
>> + proc[i].id = i;
>> + if (i == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
>> + i == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2)
>> + proc[i].handler = parse_pcc_subspace;
>> + else
>> + proc[i].handler = count_pcc_subspaces;
>> + proc[i].count = 0;
>
> Why don't you move the count initialization above the if ()?
Sure.
>> + }
>>
>> - if (sum == 0 || sum >= MAX_PCC_SUBSPACES) {
>> - pr_err("Error parsing PCC subspaces from PCCT\n");
>> + count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
>> + sizeof(struct acpi_table_pcct), proc,
>> + ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
>> + if (count == 0) {
>> + pr_warn("PCCT provided but has no subspaces defined\n");
>> + return -EINVAL;
>> + } else if (count > MAX_PCC_SUBSPACES) {
>> + pr_warn("Too many PCC subspaces defined in PCCT\n");
>
> Do we need such detailed information to be printed here? If you said
> something like "Invalid PCCT format", you could merge the two if ()
> branches.
Yeah, let me re-do these and simplify them.
>> return -EINVAL;
>> }
>>
>> pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
>> - sum, GFP_KERNEL);
>> + count, GFP_KERNEL);
>
> One line, please.
Okay.
>> if (!pcc_mbox_channels) {
>> pr_err("Could not allocate space for PCC mbox channels\n");
>> return -ENOMEM;
>> }
>>
>> - pcc_doorbell_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
>> + pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
>> if (!pcc_doorbell_vaddr) {
>> rc = -ENOMEM;
>> goto err_free_mbox;
>> }
>>
>> - pcc_doorbell_ack_vaddr = kcalloc(sum, sizeof(void *), GFP_KERNEL);
>> + pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
>> if (!pcc_doorbell_ack_vaddr) {
>> rc = -ENOMEM;
>> goto err_free_db_vaddr;
>> }
>>
>> - pcc_doorbell_irq = kcalloc(sum, sizeof(int), GFP_KERNEL);
>> + pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL);
>> if (!pcc_doorbell_irq) {
>> rc = -ENOMEM;
>> goto err_free_db_ack_vaddr;
>> @@ -509,18 +549,25 @@ static int __init acpi_pcc_probe(void)
>> if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
>> pcc_mbox_ctrl.txdone_irq = true;
>>
>> - for (i = 0; i < sum; i++) {
>> + for (i = 0; i < count; i++) {
>> struct acpi_generic_address *db_reg;
>> - struct acpi_pcct_hw_reduced *pcct_ss;
>> + struct acpi_pcct_subspace *pcct_ss;
>> pcc_mbox_channels[i].con_priv = pcct_entry;
>>
>> - pcct_ss = (struct acpi_pcct_hw_reduced *) pcct_entry;
>> + if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
>> + pcct_entry->type ==
>> + ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
>
> Again, please merge the two lines above.
Okay.
>> + struct acpi_pcct_hw_reduced *pcct_hrss;
>> +
>> + pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry;
>>
>> - if (pcc_mbox_ctrl.txdone_irq) {
>> - rc = pcc_parse_subspace_irq(i, pcct_ss);
>> - if (rc < 0)
>> - goto err;
>> + if (pcc_mbox_ctrl.txdone_irq) {
>> + rc = pcc_parse_subspace_irq(i, pcct_hrss);
>> + if (rc < 0)
>> + goto err;
>> + }
>> }
>> + pcct_ss = (struct acpi_pcct_subspace *) pcct_entry;
>>
>> /* If doorbell is in system memory cache the virt address */
>> db_reg = &pcct_ss->doorbell_register;
>> @@ -531,7 +578,7 @@ static int __init acpi_pcc_probe(void)
>> ((unsigned long) pcct_entry + pcct_entry->length);
>> }
>>
>> - pcc_mbox_ctrl.num_chans = sum;
>> + pcc_mbox_ctrl.num_chans = count;
>>
>> pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
>>
>> --
Thanks for the review, Rafael.
--
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@...hat.com
-----------------------------------
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