linux-kernel - [PATCH v3 1/2] soc: imx: gpc: Disable 6sl display power gating for ERR006287

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Message-Id: <d694bc32feb1c9638485700ba53cd6e51bea495c.1531310547.git.leonard.crestez@nxp.com>
Date:   Wed, 11 Jul 2018 15:11:16 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Lucas Stach <l.stach@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>
Cc:     Fabio Estevam <fabio.estevam@....com>, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-imx@....com, kernel@...gutronix.de
Subject: [PATCH v3 1/2] soc: imx: gpc: Disable 6sl display power gating for ERR006287

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 the safest possible way by keeping the DISP domain
always-on.

Signed-off-by: Leonard Crestez <leonard.crestez@....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..f7960f773019 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;
 
+	/* Keep DISP always on if ERR006287 is present */
+	if (of_id_data->err006287_present)
+		imx_gpc_domains[GPC_PGC_DOMAIN_DISPLAY].base.flags |=
+				GENPD_FLAG_ALWAYS_ON;
+
 	if (!pgc_node) {
 		ret = imx_gpc_old_dt_init(&pdev->dev, regmap,
 					  of_id_data->num_domains);
 		if (ret)
 			return ret;
-- 
2.17.1