linux-kernel - Re: SATA resume slowness, e1000 MSI warning

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Date:	Sun, 11 Mar 2007 05:11:59 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	"Michael S. Tsirkin" <mst@...lanox.co.il>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Kok, Auke" <auke-jan.h.kok@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Jeff Garzik <jeff@...zik.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>,
	Jens Axboe <jens.axboe@...cle.com>,
	Adrian Bunk <bunk@...sta.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>, linux-pm@...ts.osdl.org,
	Michal Piotrowski <michal.k.k.piotrowski@...il.com>
Subject: Re: SATA resume slowness, e1000 MSI warning

"Michael S. Tsirkin" <mst@...lanox.co.il> writes:

>> The only case I can see which might trigger this is if we saved
>> pci-X state and then didn't restore it because we could not find
>> the capability on restore.
>
> Hmm. pci_save_pcix_state/pci_restore_pcix_state seem to only handle
> regular devices and seem to ignore the fact that for bridge PCI-X
> capability has a different structure.
>
> Is this intentional? 

Probably not a such.  I don't think we have any drivers for bridge
devices so I don't think it matters.  It likely wouldn't hurt to fix
it just in case though.

Do any of the mellanox cards do anything with the bridge on the card?

> If not, here's a patch to fix this. Warning: completely untested.

If you fix the offsets and diff this against my last fix (to never
free the buffer) I think your patch makes sense.

> PCI: restore bridge PCI-X capability registers after PM event
>
> Restore PCI-X bridge up/downstream capability registers
> after PM event.  This includes maxumum split transaction
> commitment limit which might be vital for PCI X.
>
> Signed-off-by: Michael S. Tsirkin <mst@...lanox.co.il>
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index df49530..4b788ef 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -597,14 +597,19 @@ static int pci_save_pcix_state(struct pci_dev *dev)
>  	if (pos <= 0)
>  		return 0;
>  
> -	save_state = kzalloc(sizeof(*save_state) + sizeof(u16), GFP_KERNEL);
> + save_state = kzalloc(sizeof(*save_state) + sizeof(u16) * 2, GFP_KERNEL);
>  	if (!save_state) {
> -		dev_err(&dev->dev, "Out of memory in pci_save_pcie_state\n");
> +		dev_err(&dev->dev, "Out of memory in pci_save_pcix_state\n");
>  		return -ENOMEM;
>  	}
>  	cap = (u16 *)&save_state->data[0];
>  
> -	pci_read_config_word(dev, pos + PCI_X_CMD, &cap[i++]);
> +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {

This appears to be the proper test.

> + pci_read_config_word(dev, pos + PCI_X_BRIDGE_UP_SPL_CTL, &cap[i++]);
> + pci_read_config_word(dev, pos + PCI_X_BRIDGE_DN_SPL_CTL, &cap[i++]);
> +	} else
> +		pci_read_config_word(dev, pos + PCI_X_CMD, &cap[i++]);
> +
>  	pci_add_saved_cap(dev, save_state);
>  	return 0;
>  }
> @@ -621,7 +626,11 @@ static void pci_restore_pcix_state(struct pci_dev *dev)
>  		return;
>  	cap = (u16 *)&save_state->data[0];
>  
> -	pci_write_config_word(dev, pos + PCI_X_CMD, cap[i++]);
> +	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
> + pci_write_config_word(dev, pos + PCI_X_BRIDGE_UP_SPL_CTL, cap[i++]);
> + pci_write_config_word(dev, pos + PCI_X_BRIDGE_DN_SPL_CTL, cap[i++]);

These look like the proper two registers to save.

> +	} else
> +		pci_write_config_word(dev, pos + PCI_X_CMD, cap[i++]);
>  	pci_remove_saved_cap(save_state);
>  	kfree(save_state);
>  }
> diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
> index f09cce2..fb7eefd 100644
> --- a/include/linux/pci_regs.h
> +++ b/include/linux/pci_regs.h
> @@ -332,6 +332,8 @@
>  #define PCI_X_STATUS_SPL_ERR 0x20000000 /* Rcvd Split Completion Error Msg */
>  #define  PCI_X_STATUS_266MHZ	0x40000000	/* 266 MHz capable */
>  #define  PCI_X_STATUS_533MHZ	0x80000000	/* 533 MHz capable */
> +#define PCI_X_BRIDGE_UP_SPL_CTL 10 /* PCI-X upstream split transaction limit */
> +#define PCI_X_BRIDGE_DN_SPL_CTL 14 /* PCI-X downstream split transaction limit */

Unless I am completely misreading the spec. While you have picked the
right register to save the offsets should be 0x08 and 0x0c or 8 and 12....

Eric
-
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