[PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[Wei Yongjun]

From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>

Use for_each_pci_dev to simplify the code.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
---
 arch/tile/kernel/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
index 7598226..aac1cd5 100644
--- a/arch/tile/kernel/pci.c
+++ b/arch/tile/kernel/pci.c
@@ -245,7 +245,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
 	u16 new_values;
 
 	/* Scan for the smallest maximum payload size. */
-	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
+	for_each_pci_dev(dev) {
 		u32 devcap;
 		int max_payload;
 
@@ -260,7 +260,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
 
 	/* Now, set the max_payload_size for all devices to that value. */
 	new_values = (max_read_size << 12) | (smallest_max_payload << 5);
-	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
+	for_each_pci_dev(dev)
 		pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
 				PCI_EXP_DEVCTL_PAYLOAD | PCI_EXP_DEVCTL_READRQ,
 				new_values);

Re: [PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[Chris Metcalf]

On 12/3/2012 8:28 AM, Wei Yongjun wrote:
> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>
> Use for_each_pci_dev to simplify the code.
>
> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>

Thanks, I've taken this into my tree for -next.

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com

Re: [PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[Bjorn Helgaas]

On Mon, Dec 3, 2012 at 6:28 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>
> Use for_each_pci_dev to simplify the code.
>
> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
> ---
>  arch/tile/kernel/pci.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
> index 7598226..aac1cd5 100644
> --- a/arch/tile/kernel/pci.c
> +++ b/arch/tile/kernel/pci.c
> @@ -245,7 +245,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>         u16 new_values;
>
>         /* Scan for the smallest maximum payload size. */
> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
> +       for_each_pci_dev(dev) {
>                 u32 devcap;
>                 int max_payload;
>
> @@ -260,7 +260,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>
>         /* Now, set the max_payload_size for all devices to that value. */
>         new_values = (max_read_size << 12) | (smallest_max_payload << 5);
> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
> +       for_each_pci_dev(dev)
>                 pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
>                                 PCI_EXP_DEVCTL_PAYLOAD | PCI_EXP_DEVCTL_READRQ,
>                                 new_values);
>
>

This patch looks correct to me, as far as it goes.

Of course, any time we use for_each_pci_dev(), it's a good clue that
this code won't work for hotplug, so presumably you don't care about
hotplug on this system.

tile/kernel/pci_gx.c has a function of the same name, implemented
completely differently, which suggests that some unification or
refactoring might be possible.

In general, I think the PCI_EXP_DEVCAP and PCI_EXP_DEVCTL code for MPS
and MRRS management belongs in the PCI core, not in drivers or
architectures (it's fine if they provide device- or platform-specific
constraints), so anything you can do to move in that direction would
be good.

Bjorn

Re: [PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[Chris Metcalf]

On 12/4/2012 2:57 PM, Bjorn Helgaas wrote:
> On Mon, Dec 3, 2012 at 6:28 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
>> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>
>> Use for_each_pci_dev to simplify the code.
>>
>> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>> ---
>>  arch/tile/kernel/pci.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
>> index 7598226..aac1cd5 100644
>> --- a/arch/tile/kernel/pci.c
>> +++ b/arch/tile/kernel/pci.c
>> @@ -245,7 +245,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>>         u16 new_values;
>>
>>         /* Scan for the smallest maximum payload size. */
>> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
>> +       for_each_pci_dev(dev) {
>>                 u32 devcap;
>>                 int max_payload;
>>
>> @@ -260,7 +260,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>>
>>         /* Now, set the max_payload_size for all devices to that value. */
>>         new_values = (max_read_size << 12) | (smallest_max_payload << 5);
>> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
>> +       for_each_pci_dev(dev)
>>                 pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
>>                                 PCI_EXP_DEVCTL_PAYLOAD | PCI_EXP_DEVCTL_READRQ,
>>                                 new_values);
>>
>>
> This patch looks correct to me, as far as it goes.
>
> Of course, any time we use for_each_pci_dev(), it's a good clue that
> this code won't work for hotplug, so presumably you don't care about
> hotplug on this system.

Hotplug development is under way at the moment.

> tile/kernel/pci_gx.c has a function of the same name, implemented
> completely differently, which suggests that some unification or
> refactoring might be possible.

Sorry, which function are you referring to?  You mention MPS/MRS so perhaps you're talking about fixup_read_and_payload_sizes()?

> In general, I think the PCI_EXP_DEVCAP and PCI_EXP_DEVCTL code for MPS
> and MRRS management belongs in the PCI core, not in drivers or
> architectures (it's fine if they provide device- or platform-specific
> constraints), so anything you can do to move in that direction would
> be good.
>
> Bjorn

Thanks!

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com

Re: [PATCH -next] tile/PCI: use for_each_pci_dev to simplify the code

[Bjorn Helgaas]

On Tue, Dec 4, 2012 at 1:05 PM, Chris Metcalf <cmetcalf@tilera.com> wrote:
> On 12/4/2012 2:57 PM, Bjorn Helgaas wrote:
>> On Mon, Dec 3, 2012 at 6:28 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
>>> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>>
>>> Use for_each_pci_dev to simplify the code.
>>>
>>> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>> ---
>>>  arch/tile/kernel/pci.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
>>> index 7598226..aac1cd5 100644
>>> --- a/arch/tile/kernel/pci.c
>>> +++ b/arch/tile/kernel/pci.c
>>> @@ -245,7 +245,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>>>         u16 new_values;
>>>
>>>         /* Scan for the smallest maximum payload size. */
>>> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
>>> +       for_each_pci_dev(dev) {
>>>                 u32 devcap;
>>>                 int max_payload;
>>>
>>> @@ -260,7 +260,7 @@ static void __devinit fixup_read_and_payload_sizes(void)
>>>
>>>         /* Now, set the max_payload_size for all devices to that value. */
>>>         new_values = (max_read_size << 12) | (smallest_max_payload << 5);
>>> -       while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
>>> +       for_each_pci_dev(dev)
>>>                 pcie_capability_clear_and_set_word(dev, PCI_EXP_DEVCTL,
>>>                                 PCI_EXP_DEVCTL_PAYLOAD | PCI_EXP_DEVCTL_READRQ,
>>>                                 new_values);
>>>
>>>
>> This patch looks correct to me, as far as it goes.
>>
>> Of course, any time we use for_each_pci_dev(), it's a good clue that
>> this code won't work for hotplug, so presumably you don't care about
>> hotplug on this system.
>
> Hotplug development is under way at the moment.
>
>> tile/kernel/pci_gx.c has a function of the same name, implemented
>> completely differently, which suggests that some unification or
>> refactoring might be possible.
>
> Sorry, which function are you referring to?  You mention MPS/MRS so perhaps you're talking about fixup_read_and_payload_sizes()?

Yes, sorry I didn't make that more clear.  Both tile and tile-gx have
fixup_read_and_payload_sizes() implementations.

>> In general, I think the PCI_EXP_DEVCAP and PCI_EXP_DEVCTL code for MPS
>> and MRRS management belongs in the PCI core, not in drivers or
>> architectures (it's fine if they provide device- or platform-specific
>> constraints), so anything you can do to move in that direction would
>> be good.
>>
>> Bjorn
>
> Thanks!
>
> --
> Chris Metcalf, Tilera Corp.
> http://www.tilera.com
>