[PATCH v5 4/5] ata: ahci_imx: Enlarge RX water mark for i.MX8QM SATA

[Frank Li]

On Fri, Aug 02, 2024 at 02:46:52PM +0800, Richard Zhu wrote:
> 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.
>
> Signed-off-by: Richard Zhu <hongxing.zhu at nxp.com>

This is bug fix. need fix tag and cc stable

Frank
> ---
>  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 4dd98368f8562..627b36cc4b5c1 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_PTC			= 0xc8,
> +	IMX8QM_SATA_AHCI_PTC_RXWM_MASK		= GENMASK(6, 0),
> +	IMX8QM_SATA_AHCI_PTC_RXWM		= 0x29,
>  };
>
>  enum ahci_imx_type {
> @@ -466,6 +470,12 @@ static int imx8_sata_enable(struct ahci_host_priv *hpriv)
>  	phy_power_off(imxpriv->cali_phy0);
>  	phy_exit(imxpriv->cali_phy0);
>
> +	/* RxWaterMark setting */
> +	val = readl(hpriv->mmio + IMX8QM_SATA_AHCI_PTC);
> +	val &= ~IMX8QM_SATA_AHCI_PTC_RXWM_MASK;
> +	val |= IMX8QM_SATA_AHCI_PTC_RXWM;
> +	writel(val, hpriv->mmio + IMX8QM_SATA_AHCI_PTC);
> +
>  	return 0;
>
>  err_sata_phy_exit:
> --
> 2.37.1
>