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

Rob Clark
2019-06-30T15:03:13Z

From: Rob Clark <robdclark@chromium.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@chromium.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