Re: [PATCH] PCI: PM: Fix PCIe MRRS restoring for Loongson

[Bjorn Helgaas <helgaas@kernel.org>]

On Sun, Jun 23, 2024 at 11:39:40AM +0800, Huacai Chen wrote:
> Don't limit MRRS during resume, so that saved value can be restored,
> otherwise the MRRS will become the minimum value after resume.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 8b3517f88ff2983f ("PCI: loongson: Prevent LS7A MRRS increases")
> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>  drivers/pci/pci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 35fb1f17a589..bfc806d9e9bd 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -31,6 +31,7 @@
>  #include <asm/dma.h>
>  #include <linux/aer.h>
>  #include <linux/bitfield.h>
> +#include <linux/suspend.h>
>  #include "pci.h"
>  
>  DEFINE_MUTEX(pci_slot_mutex);
> @@ -5945,7 +5946,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq)
>  
>  	v = FIELD_PREP(PCI_EXP_DEVCTL_READRQ, ffs(rq) - 8);
>  
> -	if (bridge->no_inc_mrrs) {
> +	if (bridge->no_inc_mrrs && (pm_suspend_target_state == PM_SUSPEND_ON)) {

I don't think we can check pm_suspend_target_state here.  That seems
like a layering/encapsulation problem.  Are we failing to save this
state at suspend?  Seems like something we should address more
explicitly higher up in the suspend/resume path where we save/restore
config space.

>  		int max_mrrs = pcie_get_readrq(dev);
>  
>  		if (rq > max_mrrs) {
> -- 
> 2.43.0
>