On 23.01.23 21:18, John Watts wrote:
> When calibration fails it will clobber the existing configuration,
> even if the configuration was working but not ideal.
>
> Reverting calibration from a known bad value to a possibly good value
> gives a better chance of the memory working.
>
> I've tested this on the Novena board and had good success with it.
> U-Boot implements a similar solution in its write level calibration.
>
> Signed-off-by: John Watts <contact@xxxxxxxxxx>
> ---
> arch/arm/mach-imx/imx6-mmdc.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-imx/imx6-mmdc.c b/arch/arm/mach-imx/imx6-mmdc.c
> index 908771626a..0d50b39566 100644
> --- a/arch/arm/mach-imx/imx6-mmdc.c
> +++ b/arch/arm/mach-imx/imx6-mmdc.c
> @@ -25,11 +25,18 @@ static bool wlcalib_failed(void __iomem *ips)
>
> int mmdc_do_write_level_calibration(void)
> {
> + u32 ldectrl[4] = {0};
Initial value never read back.
> u32 esdmisc_val, zq_val;
> int errorcount = 0;
> u32 val;
> u32 ddr_mr1 = 0x4;
>
> + /* Store current calibration data in case of failure */
> + ldectrl[0] = readl(P0_IPS + MPWLDECTRL0);
> + ldectrl[1] = readl(P0_IPS + MPWLDECTRL1);
> + ldectrl[2] = readl(P1_IPS + MPWLDECTRL0);
> + ldectrl[3] = readl(P1_IPS + MPWLDECTRL1);
> +
> /* disable DDR logic power down timer */
> val = readl((P0_IPS + MDPDC));
> val &= 0xffff00ff;
> @@ -69,8 +76,14 @@ int mmdc_do_write_level_calibration(void)
> while (readl(P0_IPS + MPWLGCR) & 0x00000001);
>
> /* check for any errors on both PHYs */
> - if (wlcalib_failed(P0_IPS) || wlcalib_failed(P1_IPS))
> + if (wlcalib_failed(P0_IPS) || wlcalib_failed(P1_IPS)) {
> + pr_debug("Calibration failed, rolling back calibration data\n");
Still you only restore P0 calibration data, even if it succeeded,
but P1 failed. Is this intended?
> + writel(ldectrl[0], P0_IPS + MPWLDECTRL0);
> + writel(ldectrl[1], P0_IPS + MPWLDECTRL1);
> + writel(ldectrl[2], P1_IPS + MPWLDECTRL0);
> + writel(ldectrl[3], P1_IPS + MPWLDECTRL1);
> errorcount++;
> + }
>
> pr_debug("Write leveling calibration completed\n");
>
--
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