linux-kernel - Re: [PATCH] ata: ahci: Skip 200 ms debounce delay for Marvell 88SE9235

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Message-ID: <1ef3e995-3f61-ef53-0d5e-03bb41a52624@opensource.wdc.com>
Date:   Fri, 28 Jan 2022 08:40:21 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ata: ahci: Skip 200 ms debounce delay for Marvell
 88SE9235

On 1/28/22 08:35, Paul Menzel wrote:
> The 200 ms delay before debouncing the PHY in `sata_link_resume()` is
> not needed for the Marvell 88SE9235.
> 
>     $ lspci -nn -s 0021:0e:00.0
>     0021:0e:00.0 SATA controller [0106]: Marvell Technology Group Ltd. 88SE9235 PCIe 2.0 x2 4-port SATA 6 Gb/s Controller [1b4b:9235] (rev 11)
> 
> So, remove it. Tested on IBM S822LC with current Linux 5.17-rc1:
> 
> Without this patch (with 200 ms delay):
> 
>     [    3.358158] ata1: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3fe881000100 irq 39
>     [    3.358175] ata2: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3fe881000180 irq 39
>     [    3.358191] ata3: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3fe881000200 irq 39
>     [    3.358207] ata4: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3fe881000280 irq 39
>     […]
>     [    3.677542] ata3: SATA link down (SStatus 0 SControl 300)
>     [    3.677719] ata4: SATA link down (SStatus 0 SControl 300)
>     [    3.839242] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
>     [    3.839828] ata2.00: ATA-10: ST1000NX0313         00LY266 00LY265IBM, BE33, max UDMA/133
>     [    3.840029] ata2.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 32), AA
>     [    3.841796] ata2.00: configured for UDMA/133
>     [    3.843231] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
>     [    3.844083] ata1.00: ATA-10: ST1000NX0313         00LY266 00LY265IBM, BE33, max UDMA/133
>     [    3.844313] ata1.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 32), AA
>     [    3.846043] ata1.00: configured for UDMA/133
> 
> With patch (no delay):
> 
>     [    3.624259] ata1: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3f e881000100 irq 39
>     [    3.624436] ata2: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3f e881000180 irq 39
>     [    3.624452] ata3: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3f e881000200 irq 39
>     [    3.624468] ata4: SATA max UDMA/133 abar m2048@...fe881000000 port 0x3f e881000280 irq 39
>     […]
>     [    3.731966] ata3: SATA link down (SStatus 0 SControl 300)
>     [    3.732069] ata4: SATA link down (SStatus 0 SControl 300)
>     [    3.897448] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
>     [    3.897678] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
>     [    3.898140] ata1.00: ATA-10: ST1000NX0313         00LY266 00LY265IBM, BE33, max UDMA/133
>     [    3.898175] ata2.00: ATA-10: ST1000NX0313         00LY266 00LY265IBM, BE33, max UDMA/133
>     [    3.898287] ata1.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 32), AA
>     [    3.898349] ata2.00: 1953525168 sectors, multi 0: LBA48 NCQ (depth 32), AA
>     [    3.900070] ata1.00: configured for UDMA/133
>     [    3.900166] ata2.00: configured for UDMA/133
> 
> Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
> ---
>  drivers/ata/ahci.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index ab5811ef5a53..edca4e8fd44e 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -582,6 +582,8 @@ static const struct pci_device_id ahci_pci_tbl[] = {
>  	  .driver_data = board_ahci_yes_fbs },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_MARVELL_EXT, 0x9230),
>  	  .driver_data = board_ahci_yes_fbs },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_MARVELL_EXT, 0x9235),
> +	  .driver_data = board_ahci_no_debounce_delay },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_TTI, 0x0642), /* highpoint rocketraid 642L */
>  	  .driver_data = board_ahci_yes_fbs },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_TTI, 0x0645), /* highpoint rocketraid 644L */

Looks good. But for the commit message, instead of the dmesg copy-paste,
could you simply write the gains in terms of shortened scan time ? That
would make it easier to understand the benefits of the patch. Also,
there is no need for the lspci output.

-- 
Damien Le Moal
Western Digital Research