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Message-ID: <5c84fbf7-46cc-adc5-c938-6518200762e5@molgen.mpg.de>
Date: Mon, 27 Dec 2021 17:32:32 +0100
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
Guenter Roeck <groeck@...omium.org>, linux-ide@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] ahci: AMD A85 FCH (Hudson D4): Skip 200 ms
debounce delay in `sata_link_resume()`
Dear Linux folks,
Am 27.12.21 um 17:26 schrieb Paul Menzel:
> Since the first commit 1da177e4c3 (Linux-2.6.12-rc2) in the Linux git
> repository, `sata_link_resume()` contains a 200 ms delay with the comment
> below.
>
>> /*
>> * Some PHYs react badly if SStatus is pounded
>> * immediately after resuming. Delay 200ms before
>> * debouncing.
>> */
>
> A lot of PHYs do not have that problem though, so delaying 200 ms increases
> the boot time by 30 percent unnecessarily for a lot of systems, making
> “instant booting” quite hard.
>
> As it’s unknown for what PHY the delay was added, create a new board
> `board_ahci_nodbdelay` with the link flag `ATA_LFLAG_NO_DB_DELAY,`, and,
> for now, configure the AMD A85 FCH (Hudson D4) to use it.
>
> On the ASUS F2A85-M PRO it reduces the Linux kernel boot time by the
> expected 200 ms from 787 ms to 585 ms.
>
> Tested on ASUS F2A85-M PRO:
>
> Without patch, i. e., with 200 ms debounce delay:
>
> […]
> [ 0.000000] DMI: ASUS F2A85-M_PRO/F2A85-M_PRO, BIOS 4.15-671-g7b043ef855 12/27/2021
> […]
> [ 0.404885] ahci 0000:00:11.0: version 3.0
> [ 0.405466] ahci 0000:00:11.0: AHCI 0001.0300 32 slots 8 ports 6 Gbps 0x40 impl SATA mode
> [ 0.405470] ahci 0000:00:11.0: flags: 64bit ncq sntf ilck led clo pio
> [ 0.408036] scsi host0: ahci
> [ 0.408537] scsi host1: ahci
> [ 0.408932] scsi host2: ahci
> [ 0.409444] scsi host3: ahci
> [ 0.409841] scsi host4: ahci
> [ 0.410266] scsi host5: ahci
> [ 0.410661] scsi host6: ahci
> [ 0.411052] scsi host7: ahci
> [ 0.411284] ata1: DUMMY
> [ 0.411286] ata2: DUMMY
> [ 0.411286] ata3: DUMMY
> [ 0.411287] ata4: DUMMY
> [ 0.411288] ata5: DUMMY
> [ 0.411289] ata6: DUMMY
> [ 0.411291] ata7: SATA max UDMA/133 abar m2048@...01cc000 port 0xf01cc400 irq 19
> [ 0.411292] ata8: DUMMY
> […]
> [ 0.422362] Key type encrypted registered
> [ 0.424903] PM: Magic number: 1:28:636
> [ 0.723979] ata7: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
> [ 0.724268] ata7.00: ATA-9: SanDisk SDSSDP064G, 2.0.0, max UDMA/133
> [ 0.724271] ata7.00: 125045424 sectors, multi 1: LBA48 NCQ (depth 32)
> [ 0.725537] ata7.00: configured for UDMA/133
> [ 0.725898] scsi 6:0:0:0: Direct-Access ATA SanDisk SDSSDP06 0 PQ: 0 ANSI: 5
> [ 0.726428] sd 6:0:0:0: [sda] 125045424 512-byte logical blocks: (64.0 GB/59.6 GiB)
> [ 0.726442] sd 6:0:0:0: [sda] Write Protect is off
> [ 0.726446] sd 6:0:0:0: [sda] Mode Sense: 00 3a 00 00
> [ 0.726464] sd 6:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> [ 0.727985] sda: sda1 sda2 sda3
> [ 0.728588] sd 6:0:0:0: [sda] Attached SCSI disk
> [ 0.738495] EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
> […]
> [ 0.786812] Run /sbin/init as init process
>
> With patch, i. e., skipping the debounce delay saves 200 ms from the boot
> as expected.
>
> […]
> [ 0.000000] DMI: ASUS F2A85-M_PRO/F2A85-M_PRO, BIOS 4.15-671-g7b043ef855 12/27/2021
> […]
> [ 0.407372] ahci 0000:00:11.0: version 3.0
> [ 0.407909] ahci 0000:00:11.0: AHCI 0001.0300 32 slots 8 ports 6 Gbps 0x40 impl SATA mode
> [ 0.407913] ahci 0000:00:11.0: flags: 64bit ncq sntf ilck led clo pio
> [ 0.410520] scsi host0: ahci
> [ 0.411017] scsi host1: ahci
> [ 0.411418] scsi host2: ahci
> [ 0.411810] scsi host3: ahci
> [ 0.412225] scsi host4: ahci
> [ 0.412614] scsi host5: ahci
> [ 0.413005] scsi host6: ahci
> [ 0.413488] scsi host7: ahci
> [ 0.413713] ata1: DUMMY
> [ 0.413715] ata2: DUMMY
> [ 0.413716] ata3: DUMMY
> [ 0.413716] ata4: DUMMY
> [ 0.413717] ata5: DUMMY
> [ 0.413718] ata6: DUMMY
> [ 0.413720] ata7: SATA max UDMA/133 abar m2048@...01cc000 port 0xf01cc400 irq 19
> [ 0.413722] ata8: DUMMY
> […]
> [ 0.425414] Key type encrypted registered
> [ 0.427873] PM: Magic number: 1:234:838
> [ 0.522131] ata7: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
> [ 0.522415] ata7.00: ATA-9: SanDisk SDSSDP064G, 2.0.0, max UDMA/133
> [ 0.522418] ata7.00: 125045424 sectors, multi 1: LBA48 NCQ (depth 32)
> [ 0.523636] ata7.00: configured for UDMA/133
> [ 0.523993] scsi 6:0:0:0: Direct-Access ATA SanDisk SDSSDP06 0 PQ: 0 ANSI: 5
> [ 0.524497] sd 6:0:0:0: [sda] 125045424 512-byte logical blocks: (64.0 GB/59.6 GiB)
> [ 0.524511] sd 6:0:0:0: [sda] Write Protect is off
> [ 0.524515] sd 6:0:0:0: [sda] Mode Sense: 00 3a 00 00
> [ 0.524534] sd 6:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> [ 0.525953] sda: sda1 sda2 sda3
> [ 0.526541] sd 6:0:0:0: [sda] Attached SCSI disk
> [ 0.536245] EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
> […]
> [ 0.585327] Run /sbin/init as init process
>
> Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: Guenter Roeck <groeck@...omium.org>
>
> ---
> drivers/ata/ahci.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> v2: Add new board to enum `board_ids`.
>
> Add the two Chromium OS developers Dmitry and Guenter to Cc, as to my
> knowledge Chromium/Chrome OS also tries to boot very fast, and the Chromium
> project has some CI infrastructure.
By the way, I do not even know what the PHY actually is, and how it can
be checked.
Maybe the original commit message for the 200 ms delay mentions the PHY,
but I have no idea how to access that history.
If the delay would be removed unconditionally, a module parameter would
probably be a good idea, so people with bad PHY’s have an easy way to
get it booting again.
Kind regards,
Paul
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index 6a2432e4adda..4f3e0603864d 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -51,6 +51,7 @@ enum board_ids {
> board_ahci,
> board_ahci_ign_iferr,
> board_ahci_mobile,
> + board_ahci_nodbdelay,
> board_ahci_nomsi,
> board_ahci_noncq,
> board_ahci_nosntf,
> @@ -141,6 +142,13 @@ static const struct ata_port_info ahci_port_info[] = {
> .udma_mask = ATA_UDMA6,
> .port_ops = &ahci_ops,
> },
> + [board_ahci_nodbdelay] = {
> + .flags = AHCI_FLAG_COMMON,
> + .link_flags = ATA_LFLAG_NO_DB_DELAY,
> + .pio_mask = ATA_PIO4,
> + .udma_mask = ATA_UDMA6,
> + .port_ops = &ahci_ops,
> + },
> [board_ahci_nomsi] = {
> AHCI_HFLAGS (AHCI_HFLAG_NO_MSI),
> .flags = AHCI_FLAG_COMMON,
> @@ -437,6 +445,7 @@ static const struct pci_device_id ahci_pci_tbl[] = {
> board_ahci_al },
> /* AMD */
> { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_HUDSON2_SATA_IDE), board_ahci },
> + { PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_HUDSON2_SATA_AHCI), board_ahci_nodbdelay },
> { PCI_VDEVICE(AMD, 0x7900), board_ahci }, /* AMD CZ */
> { PCI_VDEVICE(AMD, 0x7901), board_ahci_mobile }, /* AMD Green Sardine */
> /* AMD is using RAID class only for ahci controllers */
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