On Wed, Jan 25, 2023 at 04:41:15AM +1100, John Watts wrote: > The MPWLGCR registers clear the error bits before software can read them, > so rely on the MPWLHWERR registers for error reporting instead. > > This errata was announced in 2019 but it seems to apply to all chip revisions. > > U-Boot contains a different workaround where it instead checks the calibration > data for the result 0x001F001F (maximum delay) and flag that as a failure. > I can't find the origin of this workaround but I first saw it in the Novena > source code, though I asked Sean Cross and he suggested it was from Freescale. > > While we're at it, fix the comment implying this code only checks PHY0 in x32 > configuration. This is wrong and misleading. > > Signed-off-by: John Watts <contact@xxxxxxxxxx> > --- > Changes v1 -> v2: > - Added a wall of text explaining what the code does and why > - wlcalib_failed now reads from the ips register correctly > --- > arch/arm/mach-imx/imx6-mmdc.c | 30 +++++++++++++++++++--- > arch/arm/mach-imx/include/mach/imx6-mmdc.h | 1 + > 2 files changed, 27 insertions(+), 4 deletions(-) Applied, thanks Sascha > > diff --git a/arch/arm/mach-imx/imx6-mmdc.c b/arch/arm/mach-imx/imx6-mmdc.c > index 00b8d30d69..45e1b030d3 100644 > --- a/arch/arm/mach-imx/imx6-mmdc.c > +++ b/arch/arm/mach-imx/imx6-mmdc.c > @@ -11,6 +11,30 @@ > #include <mach/imx6-regs.h> > #include <mach/imx6.h> > > +static bool wlcalib_failed(void __iomem *ips) > +{ > + /* > + * The i.MX 6 reference manual specifies that an MMDC flags reports > + * write calibration errors in the MPWLGCR register's HW_WL_ERR field. > + * > + * ERR050070 specifies that this doesn't work and we should check > + * the MPWLHWERR register instead which reports which write leveling > + * steps succeeded or failed on a per-byte basis. > + * > + * Check each byte to see which steps succeeded. If no steps succeeded > + * then declare the calibration a failure. > + */ > + > + int i; > + > + for (i = 0; i < 4; ++i) { > + if (readb(ips + MPWLHWERR + i) == 0) > + return true; > + } > + > + return false; > +} > + > int mmdc_do_write_level_calibration(void) > { > u32 esdmisc_val, zq_val; > @@ -56,11 +80,9 @@ int mmdc_do_write_level_calibration(void) > /* Upon completion of this process the MMDC de-asserts the MPWLGCR[HW_WL_EN] */ > while (readl(P0_IPS + MPWLGCR) & 0x00000001); > > - /* check for any errors: check both PHYs for x64 configuration, if x32, check only PHY0 */ > - if ((readl(P0_IPS + MPWLGCR) & 0x00000F00) || > - (readl(P1_IPS + MPWLGCR) & 0x00000F00)) { > + /* check for any errors on both PHYs */ > + if (wlcalib_failed(P0_IPS) || wlcalib_failed(P1_IPS)) > errorcount++; > - } > > pr_debug("Write leveling calibration completed\n"); > > diff --git a/arch/arm/mach-imx/include/mach/imx6-mmdc.h b/arch/arm/mach-imx/include/mach/imx6-mmdc.h > index bda20aba17..098ba4f5bf 100644 > --- a/arch/arm/mach-imx/include/mach/imx6-mmdc.h > +++ b/arch/arm/mach-imx/include/mach/imx6-mmdc.h > @@ -18,6 +18,7 @@ > #define MPWLGCR 0x808 > #define MPWLDECTRL0 0x80c > #define MPWLDECTRL1 0x810 > +#define MPWLHWERR 0x878 > #define MPPDCMPR1 0x88c > #define MPSWDAR 0x894 > #define MPRDDLCTL 0x848 > -- > 2.39.0 > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |