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@0xf01cc000 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@0xf01cc000 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@xxxxxxxxxxxxx> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> Cc: Guenter Roeck <groeck@xxxxxxxxxxxx> --- 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. 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 */ -- 2.30.2