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

[Hongxing Zhu]

> -----Original Message-----
> From: Frank Li <frank.li at nxp.com>
> Sent: 2024年8月3日 4:46
> To: Hongxing Zhu <hongxing.zhu at nxp.com>
> Cc: robh at kernel.org; krzk+dt at kernel.org; conor+dt at kernel.org;
> shawnguo at kernel.org; l.stach at pengutronix.de; devicetree at vger.kernel.org;
> linux-pci at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux-kernel at vger.kernel.org; kernel at pengutronix.de; imx at lists.linux.dev
> Subject: Re: [PATCH v5 4/5] ata: ahci_imx: Enlarge RX water mark for i.MX8QM
> SATA
> Importance: High
> 
> 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
Hi Frank:
Thanks for your comments.
Niklas suggested not add cc stable and so on.
Here is the discussion.
https://patchwork.kernel.org/project/linux-arm-kernel/patch/1721099895-26098-4-git-send-email-hongxing.zhu@nxp.com/
So, I removed them from v4 series.

Best Regards
Richard Zhu
> 
> 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
> >