[PATCH] ata: Disable AHCI ALPM feature for Ampere Computing eMAG SATA

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 <redacted>
---
 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,

@@ -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)
--

1.8.3.1

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 <redacted>

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

2) See below

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).

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).

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

Hi Hans

Thanks for your fast response.

With regards,
Suman

Please note my new email address → stripathi@amperecomputing.com

-----Original Message-----
From: Hans de Goede <redacted> 
Sent: Monday, August 27, 2018 12:09 PM
To: Suman Tripathi <redacted>; tj@kernel.org; linux-ide@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; joe@perches.com; arnd@arndb.de; gregkh@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

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).

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