[PATCH] PCI: Avoid initialize MSI/MSIX if device power state != PCI_D0

[PATCH] PCI: Avoid initialize MSI/MSIX if device power state != PCI_D0

[Yijing Wang]

Currently, if device power state != PCI_D0, we still initialize
device MSI/MSIX, but we won't write the MSI message to device
MSI/MSIX registers. It's weird, we don't configure MSI/MSIX
registers properly, but pci_enable_msi() or pci_enable_msix()
return success, and even these registers will never be updated later.
So I think it should return error if device power state != PCI_D0.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
---
 drivers/pci/msi.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index d5f90d6..eb502f6 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -308,9 +308,7 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
 
 void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
-	if (entry->dev->current_state != PCI_D0) {
-		/* Don't touch the hardware now */
-	} else if (entry->msi_attrib.is_msix) {
+	if (entry->msi_attrib.is_msix) {
 		void __iomem *base;
 		base = entry->mask_base +
 			entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
@@ -831,7 +829,7 @@ int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
 	int status, maxvec;
 	u16 msgctl;
 
-	if (!dev->msi_cap)
+	if (!dev->msi_cap || dev->current_state != PCI_D0)
 		return -EINVAL;
 
 	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
@@ -862,7 +860,7 @@ int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
 	int ret, nvec;
 	u16 msgctl;
 
-	if (!dev->msi_cap)
+	if (!dev->msi_cap || dev->current_state != PCI_D0)
 		return -EINVAL;
 
 	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
@@ -955,7 +953,7 @@ int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
 	int status, nr_entries;
 	int i, j;
 
-	if (!entries || !dev->msix_cap)
+	if (!entries || !dev->msix_cap || dev->current_state != PCI_D0)
 		return -EINVAL;
 
 	status = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSIX);
-- 
1.7.1

Re: [PATCH] PCI: Avoid initialize MSI/MSIX if device power state != PCI_D0

[Ben Hutchings]

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On Thu, 2013-10-10 at 16:31 +0800, Yijing Wang wrote:
> Currently, if device power state != PCI_D0, we still initialize
> device MSI/MSIX, but we won't write the MSI message to device
> MSI/MSIX registers. It's weird, we don't configure MSI/MSIX
> registers properly, but pci_enable_msi() or pci_enable_msix()
> return success, and even these registers will never be updated later.
> So I think it should return error if device power state != PCI_D0.
> 
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
>  drivers/pci/msi.c |   10 ++++------
>  1 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index d5f90d6..eb502f6 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -308,9 +308,7 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
>  
>  void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
>  {
> -	if (entry->dev->current_state != PCI_D0) {
> -		/* Don't touch the hardware now */
> -	} else if (entry->msi_attrib.is_msix) {
> +	if (entry->msi_attrib.is_msix) {
[...]

As I said before, this function was being called to change IRQ
affinities during suspend/resume at a point when most PCI devices were
in D3.  If that is no longer the case then this change is probably OK.
Otherwise you should not touch this function.

Ben.

-- 
Ben Hutchings
A free society is one where it is safe to be unpopular. - Adlai Stevenson

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Re: [PATCH] PCI: Avoid initialize MSI/MSIX if device power state != PCI_D0

[Yijing Wang]

On 2013/10/10 20:15, Ben Hutchings wrote:
> On Thu, 2013-10-10 at 16:31 +0800, Yijing Wang wrote:
>> Currently, if device power state != PCI_D0, we still initialize
>> device MSI/MSIX, but we won't write the MSI message to device
>> MSI/MSIX registers. It's weird, we don't configure MSI/MSIX
>> registers properly, but pci_enable_msi() or pci_enable_msix()
>> return success, and even these registers will never be updated later.
>> So I think it should return error if device power state != PCI_D0.
>>
>> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
>> ---
>>  drivers/pci/msi.c |   10 ++++------
>>  1 files changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index d5f90d6..eb502f6 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -308,9 +308,7 @@ void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
>>  
>>  void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
>>  {
>> -	if (entry->dev->current_state != PCI_D0) {
>> -		/* Don't touch the hardware now */
>> -	} else if (entry->msi_attrib.is_msix) {
>> +	if (entry->msi_attrib.is_msix) {
> [...]
> 
> As I said before, this function was being called to change IRQ
> affinities during suspend/resume at a point when most PCI devices were
> in D3.  If that is no longer the case then this change is probably OK.
> Otherwise you should not touch this function.

Hi ben, sorry for the mistake, now I know what you worry about. I will update this patch,
keep __write_msi_msg() function not changed. Only add some guard for pci_enable_msi()/pci_enable_msix() ..

Thanks!
Yijing.

> 
> Ben.
> 


-- 
Thanks!
Yijing