On 7/11/24 17:11, 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 vaulue 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.
2 remarks:
1) this seems to be a bug/problem fix, so this likely needs a backport to stable
(Cc: stable tag) and a Fixes tag.
2) What are these magic values 0x20 and 0x29 ? Where are they defined (SoC
specs) ? Can you define the new value using a macro with a self-descriptive name ?
>
> Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> ---
> 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 0e9fddd02ee5f..9147cd14f587e 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,
> + IMX8QM_SATA_AHCI_VEND_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_VEND_PTC);
> + val &= ~IMX8QM_SATA_AHCI_VEND_PTC_RXWM_MASK;
> + val |= IMX8QM_SATA_AHCI_VEND_PTC_RXWM;
> + writel(val, hpriv->mmio + IMX8QM_SATA_AHCI_VEND_PTC);
> +
> return 0;
>
> err_sata_phy_power_on:
--
Damien Le Moal
Western Digital Research
