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Subject[PATCH 4.19 265/276] drm/omap: dsi: Fix PM for display blank with paired dss_pll calls
Date
[ Upstream commit fe4ed1b457943113ee1138c939fbdeede4af6cf3 ]

Currently dsi_display_init_dsi() calls dss_pll_enable() but it is not
paired with dss_pll_disable() in dsi_display_uninit_dsi(). This leaves
the DSS clocks enabled when the display is blanked wasting about extra
5mW of power while idle.

The clock that is left on by not calling dss_pll_disable() is
DSS_CLKCTRL bit 10 OPTFCLKEN_SYS_CLK that is the source clock for
DSI PLL.

We can fix this issue by by making the current dsi_pll_uninit() into
dsi_pll_disable(). This way we can just call dss_pll_disable() from
dsi_display_uninit_dsi() and the code becomes a bit easier to follow.

However, we need to also consider that DSI PLL can be muxed for DVI too
as pointed out by Tomi Valkeinen <tomi.valkeinen@ti.com>. In the DVI
case, we want to unconditionally disable the clocks. To get around this
issue, we separate out the DSI lane handling from dsi_pll_enable() and
dsi_pll_disable() as suggested by Tomi in an earlier experimental patch.

So we must only toggle the DSI regulator based on the vdds_dsi_enabled
flag from dsi_display_init_dsi() and dsi_display_uninit_dsi().

We need to make these two changes together to avoid breaking things
for DVI when fixing the DSI clock handling. And this all causes a
slight renumbering of the error path for dsi_display_init_dsi().

Suggested-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/omapdrm/dss/dsi.c | 60 ++++++++++++++++---------------
1 file changed, 31 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index 74467b3087218..8160954ebc257 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -1386,12 +1386,9 @@ static int dsi_pll_enable(struct dss_pll *pll)
*/
dsi_enable_scp_clk(dsi);

- if (!dsi->vdds_dsi_enabled) {
- r = regulator_enable(dsi->vdds_dsi_reg);
- if (r)
- goto err0;
- dsi->vdds_dsi_enabled = true;
- }
+ r = regulator_enable(dsi->vdds_dsi_reg);
+ if (r)
+ goto err0;

/* XXX PLL does not come out of reset without this... */
dispc_pck_free_enable(dsi->dss->dispc, 1);
@@ -1416,36 +1413,25 @@ static int dsi_pll_enable(struct dss_pll *pll)

return 0;
err1:
- if (dsi->vdds_dsi_enabled) {
- regulator_disable(dsi->vdds_dsi_reg);
- dsi->vdds_dsi_enabled = false;
- }
+ regulator_disable(dsi->vdds_dsi_reg);
err0:
dsi_disable_scp_clk(dsi);
dsi_runtime_put(dsi);
return r;
}

-static void dsi_pll_uninit(struct dsi_data *dsi, bool disconnect_lanes)
+static void dsi_pll_disable(struct dss_pll *pll)
{
+ struct dsi_data *dsi = container_of(pll, struct dsi_data, pll);
+
dsi_pll_power(dsi, DSI_PLL_POWER_OFF);
- if (disconnect_lanes) {
- WARN_ON(!dsi->vdds_dsi_enabled);
- regulator_disable(dsi->vdds_dsi_reg);
- dsi->vdds_dsi_enabled = false;
- }
+
+ regulator_disable(dsi->vdds_dsi_reg);

dsi_disable_scp_clk(dsi);
dsi_runtime_put(dsi);

- DSSDBG("PLL uninit done\n");
-}
-
-static void dsi_pll_disable(struct dss_pll *pll)
-{
- struct dsi_data *dsi = container_of(pll, struct dsi_data, pll);
-
- dsi_pll_uninit(dsi, true);
+ DSSDBG("PLL disable done\n");
}

static void dsi_dump_dsi_clocks(struct dsi_data *dsi, struct seq_file *s)
@@ -4195,11 +4181,11 @@ static int dsi_display_init_dsi(struct dsi_data *dsi)

r = dss_pll_enable(&dsi->pll);
if (r)
- goto err0;
+ return r;

r = dsi_configure_dsi_clocks(dsi);
if (r)
- goto err1;
+ goto err0;

dss_select_dsi_clk_source(dsi->dss, dsi->module_id,
dsi->module_id == 0 ?
@@ -4207,6 +4193,14 @@ static int dsi_display_init_dsi(struct dsi_data *dsi)

DSSDBG("PLL OK\n");

+ if (!dsi->vdds_dsi_enabled) {
+ r = regulator_enable(dsi->vdds_dsi_reg);
+ if (r)
+ goto err1;
+
+ dsi->vdds_dsi_enabled = true;
+ }
+
r = dsi_cio_init(dsi);
if (r)
goto err2;
@@ -4235,10 +4229,13 @@ static int dsi_display_init_dsi(struct dsi_data *dsi)
err3:
dsi_cio_uninit(dsi);
err2:
- dss_select_dsi_clk_source(dsi->dss, dsi->module_id, DSS_CLK_SRC_FCK);
+ regulator_disable(dsi->vdds_dsi_reg);
+ dsi->vdds_dsi_enabled = false;
err1:
- dss_pll_disable(&dsi->pll);
+ dss_select_dsi_clk_source(dsi->dss, dsi->module_id, DSS_CLK_SRC_FCK);
err0:
+ dss_pll_disable(&dsi->pll);
+
return r;
}

@@ -4257,7 +4254,12 @@ static void dsi_display_uninit_dsi(struct dsi_data *dsi, bool disconnect_lanes,

dss_select_dsi_clk_source(dsi->dss, dsi->module_id, DSS_CLK_SRC_FCK);
dsi_cio_uninit(dsi);
- dsi_pll_uninit(dsi, disconnect_lanes);
+ dss_pll_disable(&dsi->pll);
+
+ if (disconnect_lanes) {
+ regulator_disable(dsi->vdds_dsi_reg);
+ dsi->vdds_dsi_enabled = false;
+ }
}

static int dsi_display_enable(struct omap_dss_device *dssdev)
--
2.20.1


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