[PATCH] ata: Disable AHCI ALPM feature for Ampere Computing eMAG SATA
From: Suman Tripathi <hidden>
Date: 2018-08-27 19:13:17
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Hi Hans Thanks for your fast response. With regards, Suman Please note my new email address ? stripathi at amperecomputing.com -----Original Message----- From: Hans de Goede <redacted> Sent: Monday, August 27, 2018 12:09 PM To: Suman Tripathi <redacted>; tj at kernel.org; linux-ide at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org; joe at perches.com; arnd at arndb.de; gregkh at linuxfoundation.org Cc: Open Source Submission <redacted>; Rameshwar P Sahu <redacted>; Jens Axboe <axboe@kernel.dk> Subject: Re: [PATCH] ata: Disable AHCI ALPM feature for Ampere Computing eMAG SATA [NOTICE: This email originated from an external sender. Please be mindful of safe email handling and proprietary information protection practices.] ________________________________________________________________________________________________________________________ Hi, On 27-08-18 20:47, Suman Tripathi wrote:
Due to hardware errata, Ampere Computing eMAG SATA can't support AHCI ALPM feature. This patch disables the AHCI ALPM feature for eMAG SATA. Signed-off-by: Suman Tripathi <redacted> Signed-off-by: Rameshwar Prasad Sahu [off-list ref]
Thank you for the patch. 2 remarks: 1) The ata code is maintained by Jens Axboe (added to the Cc) now, this is a very recent change, which still has to hit MAINTAINERS [Suman Tripathi] Didn't still see him for libata subsystem. Surely will fix the comments cc him for the next version. I see him in the scsi subsystem. 2) See below
quoted hunk ↗ jump to hunk
--- drivers/ata/ahci_platform.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c index 99f9a89..0d0233e 100644 --- a/drivers/ata/ahci_platform.c +++ b/drivers/ata/ahci_platform.c@@ -26,7 +26,7 @@ #define DRV_NAME "ahci" -static const struct ata_port_info ahci_port_info = { +static struct ata_port_info ahci_port_info = { .flags = AHCI_FLAG_COMMON, .pio_mask = ATA_PIO4, .udma_mask = ATA_UDMA6,
Please do not remove const here, if you need to make a shared info struct like this non const you are usually doing something wrong (see below).
quoted hunk ↗ jump to hunk
@@ -41,6 +41,8 @@ static int ahci_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct ahci_host_priv *hpriv; + struct acpi_device_info *info; + acpi_status status; int rc; hpriv = ahci_platform_get_resources(pdev);@@ -57,6 +59,15 @@ static int ahci_probe(struct platform_device *pdev) if (of_device_is_compatible(dev->of_node, "hisilicon,hisi-ahci")) hpriv->flags |= AHCI_HFLAG_NO_FBS | AHCI_HFLAG_NO_NCQ; + status = acpi_get_object_info(ACPI_HANDLE(dev), &info); + if (ACPI_SUCCESS(status)) { + if (info->valid & ACPI_VALID_HID) { + if (!strcmp("APMC0D33", info->hardware_id.string)) + ahci_port_info.flags |= ATA_FLAG_NO_LPM; + } + ACPI_FREE(info); + } + rc = ahci_platform_init_host(pdev, hpriv, &ahci_port_info, &ahci_platform_sht); if (rc)
The normal way to get specific behavior for a specific ACPI HID is to put the HID in the ahci_acpi_match table and use the acpi_device_id field to pass some flags (or a pointer).
[Suman Tripathi] Agree on this.
So the proper way to fix this is to do something like this:
1) Add:
static const struct ata_port_info ahci_port_info_nolpm = {
.flags = AHCI_FLAG_COMMON | ATA_FLAG_NO_LPM,
.pio_mask = ATA_PIO4,
.udma_mask = ATA_UDMA6,
.port_ops = &ahci_platform_ops,
};
2) Modify ahci_acpi_match table to:
static const struct acpi_device_id ahci_acpi_match[] = {
{ "APMC0D33", (unsigned long)&ahci_port_info_nolpm },
{ ACPI_DEVICE_CLASS(PCI_CLASS_STORAGE_SATA_AHCI, 0xffffff) },
{},
};
3) In ahci_probe() do:
const struct ata_port_info *port;
...
port = acpi_device_get_match_data(dev);
if (!port)
port = &ahci_port_info;
rc = ahci_platform_init_host(pdev, hpriv, port, &ahci_platform_sht);
Regards,
Hans