From:   Adam Ford <aford173@gmail.com>
To:     linux-arm-kernel@lists.infradead.org
Cc:     tharvey@gateworks.com, aford@beaconembedded.com,
        Adam Ford <aford173@gmail.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] soc: imx: gpcv2: Enable vpumix/dispmix to wait for handshake
Date:   Sat, 20 Nov 2021 13:49:00 -0600
Message-Id: <20211120194900.1309914-1-aford173@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

There is a comment in the code that states the driver needs to
wait for the handshake, but it's only available when the bus
has been enabled from the blk-ctrl.  Since both the
vpumix and dispmix are called from the blk-ctl, it seems
reasonable to assume the bus is enabled. Add a bool to determine
which power-domains are able to properly wait for this
handshake and set the corresping boolean for the two domains
activated by the blk-ctrl.

Signed-off-by: Adam Ford <aford173@gmail.com>

diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
index 7b6dfa33dcb9..a957f7fff968 100644
--- a/drivers/soc/imx/gpcv2.c
+++ b/drivers/soc/imx/gpcv2.c
@@ -204,6 +204,7 @@ struct imx_pgc_domain {
 	const int voltage;
 	const bool keep_clocks;
 	struct device *dev;
+	bool blkctrl_bus_enabled;
 };
 
 struct imx_pgc_domain_data {
@@ -282,17 +283,14 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
 				   domain->bits.hskreq, domain->bits.hskreq);
 
 		/*
-		 * ret = regmap_read_poll_timeout(domain->regmap, GPC_PU_PWRHSK, reg_val,
-		 *				  (reg_val & domain->bits.hskack), 0,
-		 *				  USEC_PER_MSEC);
-		 * Technically we need the commented code to wait handshake. But that needs
-		 * the BLK-CTL module BUS clk-en bit being set.
-		 *
-		 * There is a separate BLK-CTL module and we will have such a driver for it,
-		 * that driver will set the BUS clk-en bit and handshake will be triggered
-		 * automatically there. Just add a delay and suppose the handshake finish
-		 * after that.
+		 * blkctrl_bus_enabled implies that the GPC is being invoked from a blk-ctrl
+		 * and not from a peripheral or other GPC power domain.  The blk-ctrl is required
+		 * to support the handshake.
 		 */
+		if (domain->blkctrl_bus_enabled)
+			ret = regmap_read_poll_timeout(domain->regmap, GPC_PU_PWRHSK, reg_val,
+							(reg_val & domain->bits.hskack), 0,
+							USEC_PER_MSEC);
 	}
 
 	/* Disable reset clocks for all devices in the domain */
@@ -701,6 +699,7 @@ static const struct imx_pgc_domain imx8mm_pgc_domains[] = {
 		},
 		.pgc   = BIT(IMX8MM_PGC_VPUMIX),
 		.keep_clocks = true,
+		.blkctrl_bus_enabled = true,
 	},
 
 	[IMX8MM_POWER_DOMAIN_VPUG1] = {
@@ -749,6 +748,7 @@ static const struct imx_pgc_domain imx8mm_pgc_domains[] = {
 		},
 		.pgc   = BIT(IMX8MM_PGC_DISPMIX),
 		.keep_clocks = true,
+		.blkctrl_bus_enabled = true,
 	},
 
 	[IMX8MM_POWER_DOMAIN_MIPI] = {
-- 
2.32.0