linux-kernel - Re: [PATCH 2/2] [RFC] ata: ahci: Skip debounce delay for AMD FCH SATA Controller

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Date:   Thu, 3 Mar 2022 14:23:01 +0200
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Mario Limonciello <mario.limonciello@....com>,
        linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] [RFC] ata: ahci: Skip debounce delay for AMD FCH SATA
 Controller

On 2022/03/03 12:04, Paul Menzel wrote:
> AMD devices with the FCH SATA Controller 0x1022:0x7901 do not need the
> default debounce delay of 200 ms.
> 
>     07:00.2 SATA controller [0106]: Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode] [1022:7901] (rev 51)
> 
> So skip it, by mapping it to the board with no debounce delay.
> 
> Tested on the MSI MS-7A37/B350M MORTAR (MS-7A37).
> 
> To-do: Add test details and results.

Please squash this patch together with patch 1. Since you are adding a new board
entry definition, it is better to have a user for it in the same patch (this
avoids reverts to leave unused code behind).

> 
> Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Mario Limonciello <mario.limonciello@....com>
> ---
> I am travelling so could not test this exact patch just yet, but I ran
> something similar for several weeks already. It’d be great, if the
> desktop and AMD folks could also give this a try.
> 
>  drivers/ata/ahci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index 0fc09b86a559..44b79fe43d13 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -456,7 +456,7 @@ static const struct pci_device_id ahci_pci_tbl[] = {
>  	{ PCI_VDEVICE(AMD, 0x7800), board_ahci }, /* AMD Hudson-2 */
>  	{ PCI_VDEVICE(AMD, 0x7801), board_ahci_no_debounce_delay }, /* AMD Hudson-2 (AHCI mode) */
>  	{ PCI_VDEVICE(AMD, 0x7900), board_ahci }, /* AMD CZ */
> -	{ PCI_VDEVICE(AMD, 0x7901), board_ahci_low_power }, /* AMD Green Sardine */
> +	{ PCI_VDEVICE(AMD, 0x7901), board_ahci_low_power_no_debounce_delay }, /* AMD Green Sardine */

Really long name, but I cannot think of anything better...

>  	/* AMD is using RAID class only for ahci controllers */
>  	{ PCI_VENDOR_ID_AMD, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>  	  PCI_CLASS_STORAGE_RAID << 8, 0xffffff, board_ahci },


-- 
Damien Le Moal
Western Digital Research