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SubjectRe: [PATCH v2 1/2] soc: imx: gpc: Disable 6sl display power gating for ERR006287
On 9 July 2018 at 14:23, Leonard Crestez <leonard.crestez@nxp.com> wrote:
> The imx6sl chip errata document describes ERR006287 like this:
>
> """
> Upon resuming from power gating, the modules in the display power domain
> (eLCDIF, EPDC, PXP and SPDC) might fail to perform register reads
> correctly.
>
> When the modules listed above are used, do not use power gating on the
> display power domain.
> """
>
> Link: https://www.nxp.com/docs/en/errata/IMX6SLCE.pdf#page=62
>
> Handle this in linux in the same way as imx6qp ERR009619: make the DISP
> domain return -EBUSY on power_off.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/soc/imx/gpc.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/soc/imx/gpc.c b/drivers/soc/imx/gpc.c
> index 526f2d02dc78..6b726dada560 100644
> --- a/drivers/soc/imx/gpc.c
> +++ b/drivers/soc/imx/gpc.c
> @@ -339,30 +339,35 @@ static struct imx_pm_domain imx_gpc_domains[] = {
> };
>
> struct imx_gpc_dt_data {
> int num_domains;
> bool err009619_present;
> + bool err006287_present;
> };
>
> static const struct imx_gpc_dt_data imx6q_dt_data = {
> .num_domains = 2,
> .err009619_present = false,
> + .err006287_present = false,
> };
>
> static const struct imx_gpc_dt_data imx6qp_dt_data = {
> .num_domains = 2,
> .err009619_present = true,
> + .err006287_present = false,
> };
>
> static const struct imx_gpc_dt_data imx6sl_dt_data = {
> .num_domains = 3,
> .err009619_present = false,
> + .err006287_present = true,
> };
>
> static const struct imx_gpc_dt_data imx6sx_dt_data = {
> .num_domains = 4,
> .err009619_present = false,
> + .err006287_present = false,
> };
>
> static const struct of_device_id imx_gpc_dt_ids[] = {
> { .compatible = "fsl,imx6q-gpc", .data = &imx6q_dt_data },
> { .compatible = "fsl,imx6qp-gpc", .data = &imx6qp_dt_data },
> @@ -467,10 +472,15 @@ static int imx_gpc_probe(struct platform_device *pdev)
> /* Disable PU power down in normal operation if ERR009619 is present */
> if (of_id_data->err009619_present)
> imx_gpc_domains[GPC_PGC_DOMAIN_PU].flags |=
> PGC_DOMAIN_FLAG_NO_PD;
>
> + /* Disable DISP power down in normal operation if ERR006287 is present */
> + if (of_id_data->err006287_present)
> + imx_gpc_domains[GPC_PGC_DOMAIN_DISPLAY].flags |=
> + PGC_DOMAIN_FLAG_NO_PD;
> +

This looks like a use-case for an always powered on PM domain?

If that's the case, GENPD_FLAG_ALWAYS_ON does the trick, but more
efficient as it enables genpd to take a few shortcuts when trying to
power of a PM domain.

> if (!pgc_node) {
> ret = imx_gpc_old_dt_init(&pdev->dev, regmap,
> of_id_data->num_domains);
> if (ret)
> return ret;
> --
> 2.17.1
>

Kind regards
Uffe

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