diff mbox series

[v4,2/2] ahci: AMD A85 FCH (Hudson D4): Skip 200 ms debounce delay in `sata_link_resume()`

Message ID 20220105153618.2395-2-pmenzel@molgen.mpg.de
State New
Headers show
Series [v4,1/2] ahci: Rename flag `ATA_LFLAG_NO_DB_DELAY` to `ATA_LFLAG_NO_DEBOUNCE_DELAY` | expand

Commit Message

Paul Menzel Jan. 5, 2022, 3:36 p.m. UTC 
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@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

[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@molgen.mpg.de>
Cc: Tejun Heo <tj@kernel.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 mbox series

Patch

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 */