linux-kernel - [PATCH 4/5] drm/msm/dsi: get the clocks into OFF state at init

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Date:   Sun, 30 Jun 2019 08:01:42 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org
Cc:     freedreno@...ts.freedesktop.org, aarch64-laptops@...ts.linaro.org,
        linux-clk@...r.kernel.org, linux-pm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Mamta Shukla <mamtashukla555@...il.com>,
        Chandan Uddaraju <chandanu@...eaurora.org>,
        Archit Taneja <architt@...eaurora.org>,
        Rajesh Yadav <ryadav@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] drm/msm/dsi: get the clocks into OFF state at init

From: Rob Clark <robdclark@...omium.org>

Do an extra enable/disable cycle at init, to get the clks into disabled
state in case bootloader left them enabled.

In case they were already enabled, the clk_prepare_enable() has no real
effect, other than getting the enable_count/prepare_count into the right
state so that we can disable clocks in the correct order.  This way we
avoid having stuck clocks when we later want to do a modeset and set the
clock rates.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c         | 18 +++++++++++++++---
 drivers/gpu/drm/msm/dsi/pll/dsi_pll_10nm.c |  1 +
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 87119d0afb91..d6e81f330db4 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -215,8 +215,6 @@ static const struct msm_dsi_cfg_handler *dsi_get_config(
 		goto put_gdsc;
 	}
 
-	pm_runtime_get_sync(dev);
-
 	ret = regulator_enable(gdsc_reg);
 	if (ret) {
 		pr_err("%s: unable to enable gdsc\n", __func__);
@@ -243,7 +241,6 @@ static const struct msm_dsi_cfg_handler *dsi_get_config(
 	clk_disable_unprepare(ahb_clk);
 disable_gdsc:
 	regulator_disable(gdsc_reg);
-	pm_runtime_put_sync(dev);
 put_gdsc:
 	regulator_put(gdsc_reg);
 exit:
@@ -390,6 +387,8 @@ static int dsi_clk_init(struct msm_dsi_host *msm_host)
 				__func__, cfg->bus_clk_names[i], ret);
 			goto exit;
 		}
+
+		clk_prepare_enable(msm_host->bus_clks[i]);
 	}
 
 	/* get link and source clocks */
@@ -436,6 +435,16 @@ static int dsi_clk_init(struct msm_dsi_host *msm_host)
 
 	if (cfg_hnd->ops->clk_init_ver)
 		ret = cfg_hnd->ops->clk_init_ver(msm_host);
+
+	/*
+	 * Do an extra enable/disable sequence initially to ensure the
+	 * clocks are actually off, if left enabled by bootloader..
+	 */
+	ret = cfg_hnd->ops->link_clk_enable(msm_host);
+	if (!ret)
+		cfg_hnd->ops->link_clk_disable(msm_host);
+	ret = 0;
+
 exit:
 	return ret;
 }
@@ -1855,6 +1864,7 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi)
 	}
 
 	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
 
 	msm_host->cfg_hnd = dsi_get_config(msm_host);
 	if (!msm_host->cfg_hnd) {
@@ -1885,6 +1895,8 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi)
 		goto fail;
 	}
 
+	pm_runtime_put_sync(&pdev->dev);
+
 	msm_host->rx_buf = devm_kzalloc(&pdev->dev, SZ_4K, GFP_KERNEL);
 	if (!msm_host->rx_buf) {
 		ret = -ENOMEM;
diff --git a/drivers/gpu/drm/msm/dsi/pll/dsi_pll_10nm.c b/drivers/gpu/drm/msm/dsi/pll/dsi_pll_10nm.c
index aabab6311043..d0172d8db882 100644
--- a/drivers/gpu/drm/msm/dsi/pll/dsi_pll_10nm.c
+++ b/drivers/gpu/drm/msm/dsi/pll/dsi_pll_10nm.c
@@ -354,6 +354,7 @@ static int dsi_pll_10nm_lock_status(struct dsi_pll_10nm *pll)
 	if (rc)
 		pr_err("DSI PLL(%d) lock failed, status=0x%08x\n",
 		       pll->id, status);
+rc = 0; // HACK, this will fail if PLL already running..
 
 	return rc;
 }
-- 
2.20.1