-----Original Message-----
From: Damien Le Moal <dlemoal@kernel.org>
Sent: 2024年7月16日 6:01
To: Hongxing Zhu <hongxing.zhu@nxp.com>; tj@kernel.org; cassel@kernel.org;
robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org;
shawnguo@kernel.org; s.hauer@pengutronix.de; festevam@gmail.com
Cc: linux-ide@vger.kernel.org; stable@vger.kernel.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
linux-arm-kernel@lists.infradead.org; imx@lists.linux.dev;
kernel@pengutronix.de
Subject: Re: [PATCH v2 3/4] ata: ahci_imx: Enlarge RX water mark for i.MX8QM
SATA

On 7/15/24 10:53, Richard Zhu wrote:

quoted

The RXWM(RxWaterMark) sets the minimum number of free location within
the RX FIFO before the watermark is exceeded which in turn will cause
the Transport Layer to instruct the Link Layer to transmit HOLDS to
the transmitting end.

Based on the default RXWM value 0x20, RX FIFO overflow might be
observed on i.MX8QM MEK board, when some Gen3 SATA disks are used.

The FIFO overflow will result in CRC error, internal error and
protocol error, then the SATA link is not stable anymore.

To fix this issue, enlarge RX water mark setting from 0x20 to 0x29.

Fixes: 027fa4dee935 ("ahci: imx: add the imx8qm ahci sata support")
Cc: stable@vger.kernel.org
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
 drivers/ata/ahci_imx.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/ata/ahci_imx.c b/drivers/ata/ahci_imx.c index

e94c0fdea2260..12d69a6429b6a 100644

--- a/drivers/ata/ahci_imx.c
+++ b/drivers/ata/ahci_imx.c

@@ -45,6 +45,10 @@ enum {
 	/* Clock Reset Register */
 	IMX_CLOCK_RESET				= 0x7f3f,
 	IMX_CLOCK_RESET_RESET			= 1 << 0,
+	/* IMX8QM SATA specific control registers */
+	IMX8QM_SATA_AHCI_VEND_PTC		= 0xc8,
+	IMX8QM_SATA_AHCI_VEND_PTC_RXWM_MASK	= 0x7f,

Please use GENMASK() macro to define this.

Thanks for your comments.
Okay.

quoted

+	IMX8QM_SATA_AHCI_VEND_PTC_NEWRXWM	= 0x29,

Here too. And I do not see the point of the "NEW" in the macro name.

Okay, "NEW" would be removed.

Also, what is "_VEND_" supposed to mean in the macro names ? "Vendor" ?
If that is the case, remove that too, which will give you shorter macro names.
If not, then spell it out because that is not clear.

Yes, you're right.
"_VEND_" means "Vendor". I would remove them later.

Best Regards
Richard Zhu

quoted

 };

 enum ahci_imx_type {

@@ -466,6 +470,12 @@ static int imx8_sata_enable(struct ahci_host_priv

*hpriv)

quoted

 	phy_power_off(imxpriv->cali_phy0);
 	phy_exit(imxpriv->cali_phy0);

+	/* RxWaterMark setting */
+	val = readl(hpriv->mmio + IMX8QM_SATA_AHCI_VEND_PTC);
+	val &= ~IMX8QM_SATA_AHCI_VEND_PTC_RXWM_MASK;
+	val |= IMX8QM_SATA_AHCI_VEND_PTC_NEWRXWM;
+	writel(val, hpriv->mmio + IMX8QM_SATA_AHCI_VEND_PTC);
+
 	return 0;

 err_sata_phy_exit:

--
Damien Le Moal
Western Digital Research