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Message-Id: <20220105153618.2395-2-pmenzel@molgen.mpg.de>
Date: Wed, 5 Jan 2022 16:36:18 +0100
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc: Paul Menzel <pmenzel@...gen.mpg.de>, Tejun Heo <tj@...nel.org>,
linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/2] ahci: AMD A85 FCH (Hudson D4): Skip 200 ms debounce delay in `sata_link_resume()`
Commit 4effb658a0 from October 2003 [1, historical git archive] with the
commit message
> [libata] Merge Serial ATA core, and drivers for:
>
> Intel ICH5 (production)
> ServerWorks / Apple K2 (beta)
> VIA (beta)
> Silicon Image 3112 (broken!)
> Various Promise (alpha/beta)
adds the code below:
void sata_phy_reset(struct ata_port *ap)
{
[…]
/* wait for phy to become ready, if necessary */
do {
msleep(200);
sstatus = scr_read(ap, SCR_STATUS);
if ((sstatus & 0xf) != 1)
break;
} while (time_before(jiffies, timeout));
[…]
}
Later on in commit d7bb4cc75759 ([PATCH] libata-hp-prep: implement
sata_phy_debounce()) the commit is refactored [2], and the comment
clarified.
/*
* Writes to SControl sometimes get ignored under certain
* controllers (ata_piix SIDPR). Make sure DET actually is
* cleared.
*/
do {
scontrol = (scontrol & 0x0f0) | 0x300;
if ((rc = sata_scr_write(link, SCR_CONTROL, scontrol)))
return rc;
/*
* Some PHYs react badly if SStatus is pounded
* immediately after resuming. Delay 200ms before
* debouncing.
*/
if (!(link->flags & ATA_LFLAG_NO_DEBOUNCE_DELAY))
ata_msleep(link->ap, 200);
/* is SControl restored correctly? */
if ((rc = sata_scr_read(link, SCR_CONTROL, &scontrol)))
return rc;
} while ((scontrol & 0xf0f) != 0x300 && --tries);
A lot of PHYs do not need a delay 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_no_debounce_delay` with the link flag
`ATA_LFLAG_NO_DEBOUNCE_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
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=4effb658a0f800e159c29a2d881cac76c326087a
[2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d7bb4cc7575929a60b0a718daa1bce87bea9a9cc
Signed-off-by: Paul Menzel <pmenzel@...gen.mpg.de>
Cc: Tejun Heo <tj@...nel.org>
---
v4:
1. Use 0x7801 instead of macros
2. Use clearer name `no_debounce_delay` over `nodbdelay`
3. Provide more history in commit message
drivers/ata/ahci.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 1e1167e725a40..836b763c640fc 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_no_debounce_delay,
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_no_debounce_delay] = {
+ .flags = AHCI_FLAG_COMMON,
+ .link_flags = ATA_LFLAG_NO_DEBOUNCE_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, 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_mobile }, /* AMD Green Sardine */
/* AMD is using RAID class only for ahci controllers */
--
2.30.2
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