PCI: set BAR size bits correctly in Resize BAR control register
diff mbox series

Message ID 20190716180940.17828-1-sumit.saxena@broadcom.com
State Superseded
Headers show
Series
  • PCI: set BAR size bits correctly in Resize BAR control register
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Commit Message

Sumit Saxena July 16, 2019, 6:09 p.m. UTC
In Resize BAR control register, bits[8:12] represents size of BAR.
As per PCIe specification, below is encoded values in register bits
to actual BAR size table:

Bits  BAR size
0     1 MB
1     2 MB
2     4 MB
3     8 MB
--

For 1 MB BAR size, BAR size bits should be set to 0 but incorrectly
these bits are set to "1f". 
Latest megaraid_sas and mpt3sas adapters which support Resizable BAR 
with 1 MB BAR size fails to initialize during system resume from S3 sleep.

Fix: Correctly set BAR size bits to "0" for 1MB BAR size.

CC: stable@vger.kernel.org # v4.16+
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203939
Fixes: d3252ace0bc652a1a244455556b6a549f969bf99 ("PCI: Restore resized BAR state on resume")
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
---
 drivers/pci/pci.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Sumit Saxena July 19, 2019, 5:56 p.m. UTC | #1
+Christian Koenig

On Tue, Jul 16, 2019 at 3:41 PM Sumit Saxena <sumit.saxena@broadcom.com> wrote:
>
> In Resize BAR control register, bits[8:12] represents size of BAR.
> As per PCIe specification, below is encoded values in register bits
> to actual BAR size table:
>
> Bits  BAR size
> 0     1 MB
> 1     2 MB
> 2     4 MB
> 3     8 MB
> --
>
> For 1 MB BAR size, BAR size bits should be set to 0 but incorrectly
> these bits are set to "1f".
> Latest megaraid_sas and mpt3sas adapters which support Resizable BAR
> with 1 MB BAR size fails to initialize during system resume from S3 sleep.
>
> Fix: Correctly set BAR size bits to "0" for 1MB BAR size.
>
> CC: stable@vger.kernel.org # v4.16+
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203939
> Fixes: d3252ace0bc652a1a244455556b6a549f969bf99 ("PCI: Restore resized BAR state on resume")
> Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
> ---
>  drivers/pci/pci.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8abc843..b651f32 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1417,12 +1417,13 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
>
>         for (i = 0; i < nbars; i++, pos += 8) {
>                 struct resource *res;
> -               int bar_idx, size;
> +               int bar_idx, size, order;
>
>                 pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
>                 bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
>                 res = pdev->resource + bar_idx;
> -               size = order_base_2((resource_size(res) >> 20) | 1) - 1;
> +               order = order_base_2((resource_size(res) >> 20) | 1);
> +               size = order ? order - 1 : 0;
>                 ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
>                 ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
>                 pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
> --
> 1.8.3.1
>
Koenig, Christian July 21, 2019, 2:47 p.m. UTC | #2
Am 19.07.19 um 19:56 schrieb Sumit Saxena:
> +Christian Koenig
>
> On Tue, Jul 16, 2019 at 3:41 PM Sumit Saxena <sumit.saxena@broadcom.com> wrote:
>> In Resize BAR control register, bits[8:12] represents size of BAR.
>> As per PCIe specification, below is encoded values in register bits
>> to actual BAR size table:
>>
>> Bits  BAR size
>> 0     1 MB
>> 1     2 MB
>> 2     4 MB
>> 3     8 MB
>> --
>>
>> For 1 MB BAR size, BAR size bits should be set to 0 but incorrectly
>> these bits are set to "1f".
>> Latest megaraid_sas and mpt3sas adapters which support Resizable BAR
>> with 1 MB BAR size fails to initialize during system resume from S3 sleep.
>>
>> Fix: Correctly set BAR size bits to "0" for 1MB BAR size.
>>
>> CC: stable@vger.kernel.org # v4.16+
>> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203939
>> Fixes: d3252ace0bc652a1a244455556b6a549f969bf99 ("PCI: Restore resized BAR state on resume")
>> Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
>> ---
>>   drivers/pci/pci.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 8abc843..b651f32 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -1417,12 +1417,13 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
>>
>>          for (i = 0; i < nbars; i++, pos += 8) {
>>                  struct resource *res;
>> -               int bar_idx, size;
>> +               int bar_idx, size, order;
>>
>>                  pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
>>                  bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
>>                  res = pdev->resource + bar_idx;
>> -               size = order_base_2((resource_size(res) >> 20) | 1) - 1;
>> +               order = order_base_2((resource_size(res) >> 20) | 1);
>> +               size = order ? order - 1 : 0;

That actually doesn't looks like it is correct or at least it's 
unnecessary complex.

The " >> 20) | 1" seems like a copy & paste error from the code in 
amdgpu where the BAR needs to larger than the VRAM size (which is not a 
power of two).

So just using "size = order_base_2(resource_size(res) >> 20);" should be 
sufficient here.

Regards,
Christian.

>>                  ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
>>                  ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
>>                  pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
>> --
>> 1.8.3.1
>>
Sumit Saxena July 21, 2019, 3:09 p.m. UTC | #3
On Sun, Jul 21, 2019 at 8:17 PM Koenig, Christian
<Christian.Koenig@amd.com> wrote:
>
> Am 19.07.19 um 19:56 schrieb Sumit Saxena:
> > +Christian Koenig
> >
> > On Tue, Jul 16, 2019 at 3:41 PM Sumit Saxena <sumit.saxena@broadcom.com> wrote:
> >> In Resize BAR control register, bits[8:12] represents size of BAR.
> >> As per PCIe specification, below is encoded values in register bits
> >> to actual BAR size table:
> >>
> >> Bits  BAR size
> >> 0     1 MB
> >> 1     2 MB
> >> 2     4 MB
> >> 3     8 MB
> >> --
> >>
> >> For 1 MB BAR size, BAR size bits should be set to 0 but incorrectly
> >> these bits are set to "1f".
> >> Latest megaraid_sas and mpt3sas adapters which support Resizable BAR
> >> with 1 MB BAR size fails to initialize during system resume from S3 sleep.
> >>
> >> Fix: Correctly set BAR size bits to "0" for 1MB BAR size.
> >>
> >> CC: stable@vger.kernel.org # v4.16+
> >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203939
> >> Fixes: d3252ace0bc652a1a244455556b6a549f969bf99 ("PCI: Restore resized BAR state on resume")
> >> Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
> >> ---
> >>   drivers/pci/pci.c | 5 +++--
> >>   1 file changed, 3 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> >> index 8abc843..b651f32 100644
> >> --- a/drivers/pci/pci.c
> >> +++ b/drivers/pci/pci.c
> >> @@ -1417,12 +1417,13 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
> >>
> >>          for (i = 0; i < nbars; i++, pos += 8) {
> >>                  struct resource *res;
> >> -               int bar_idx, size;
> >> +               int bar_idx, size, order;
> >>
> >>                  pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> >>                  bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
> >>                  res = pdev->resource + bar_idx;
> >> -               size = order_base_2((resource_size(res) >> 20) | 1) - 1;
> >> +               order = order_base_2((resource_size(res) >> 20) | 1);
> >> +               size = order ? order - 1 : 0;
>
> That actually doesn't looks like it is correct or at least it's
> unnecessary complex.
>
> The " >> 20) | 1" seems like a copy & paste error from the code in
> amdgpu where the BAR needs to larger than the VRAM size (which is not a
> power of two).
>
> So just using "size = order_base_2(resource_size(res) >> 20);" should be
> sufficient here.
Agreed, thanks for feedback. I will send simplified version of the
patch using just-
"size = order_base_2(resource_size(res) >> 20);".

Thanks,
Sumit
>
> Regards,
> Christian.
>
> >>                  ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
> >>                  ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
> >>                  pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
> >> --
> >> 1.8.3.1
> >>
>

Patch
diff mbox series

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8abc843..b651f32 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1417,12 +1417,13 @@  static void pci_restore_rebar_state(struct pci_dev *pdev)
 
 	for (i = 0; i < nbars; i++, pos += 8) {
 		struct resource *res;
-		int bar_idx, size;
+		int bar_idx, size, order;
 
 		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
 		bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
 		res = pdev->resource + bar_idx;
-		size = order_base_2((resource_size(res) >> 20) | 1) - 1;
+		order = order_base_2((resource_size(res) >> 20) | 1);
+		size = order ? order - 1 : 0;
 		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
 		ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
 		pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);