Re: [RFC PATCH 02/10] drm/panel: s6e63m0: Don't store+check prepared/enabled

[Doug Anderson]

Hi,

On Fri, Aug 4, 2023 at 2:07 PM Douglas Anderson  wrote:
>
> As talked about in commit d2aacaf07395 ("drm/panel: Check for already
> prepared/enabled in drm_panel"), we want to remove needless code from
> panel drivers that was storing and double-checking the
> prepared/enabled state. Even if someone was relying on the
> double-check before, that double-check is now in the core and not
> needed in individual drivers.
>
> For the s6e63m0 panel driver, this actually fixes a subtle/minor error
> handling bug in s6e63m0_prepare(). In one error case s6e63m0_prepare()
> called s6e63m0_unprepare() directly if there was an error. This call
> to s6e63m0_unprepare() would have been a no-op since ctx->prepared
> wasn't set yet.
>
> Signed-off-by: Douglas Anderson 
> ---
>
>  drivers/gpu/drm/panel/panel-samsung-s6e63m0.c | 25 ---
>  1 file changed, 25 deletions(-)

In response to the cover letter [1], I proposed landing patches #1-#3
directly from here while we resolve the issues talked about in
response to patch #4 [2]. I didn't hear any complaints, so I took
Linus W's review tag from the cover letter and pushed this to
drm-misc-next.

d43f0fe153dc drm/panel: s6e63m0: Don't store+check prepared/enabled

[1] 
https://lore.kernel.org/r/CAD=FV=ufuusrrzmkl8_rl5wlvkjrydwrsay_pwta-hx_p0d...@mail.gmail.com
[2] 
https://lore.kernel.org/r/20230804140605.RFC.4.I930069a32baab6faf46d6b234f89613b5cec0f14@changeid/

[RFC PATCH 02/10] drm/panel: s6e63m0: Don't store+check prepared/enabled

[Douglas Anderson]

As talked about in commit d2aacaf07395 ("drm/panel: Check for already
prepared/enabled in drm_panel"), we want to remove needless code from
panel drivers that was storing and double-checking the
prepared/enabled state. Even if someone was relying on the
double-check before, that double-check is now in the core and not
needed in individual drivers.

For the s6e63m0 panel driver, this actually fixes a subtle/minor error
handling bug in s6e63m0_prepare(). In one error case s6e63m0_prepare()
called s6e63m0_unprepare() directly if there was an error. This call
to s6e63m0_unprepare() would have been a no-op since ctx->prepared
wasn't set yet.

Signed-off-by: Douglas Anderson 
---

 drivers/gpu/drm/panel/panel-samsung-s6e63m0.c | 25 ---
 1 file changed, 25 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e63m0.c 
b/drivers/gpu/drm/panel/panel-samsung-s6e63m0.c
index b34fa4d5de07..a0e5698275a5 100644
--- a/drivers/gpu/drm/panel/panel-samsung-s6e63m0.c
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e63m0.c
@@ -270,9 +270,6 @@ struct s6e63m0 {
struct regulator_bulk_data supplies[2];
struct gpio_desc *reset_gpio;
 
-   bool prepared;
-   bool enabled;
-
/*
 * This field is tested by functions directly accessing bus before
 * transfer, transfer is skipped if it is set. In case of transfer
@@ -502,9 +499,6 @@ static int s6e63m0_disable(struct drm_panel *panel)
 {
struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 
-   if (!ctx->enabled)
-   return 0;
-
backlight_disable(ctx->bl_dev);
 
s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_OFF);
@@ -512,8 +506,6 @@ static int s6e63m0_disable(struct drm_panel *panel)
s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
msleep(120);
 
-   ctx->enabled = false;
-
return 0;
 }
 
@@ -522,17 +514,12 @@ static int s6e63m0_unprepare(struct drm_panel *panel)
struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
int ret;
 
-   if (!ctx->prepared)
-   return 0;
-
s6e63m0_clear_error(ctx);
 
ret = s6e63m0_power_off(ctx);
if (ret < 0)
return ret;
 
-   ctx->prepared = false;
-
return 0;
 }
 
@@ -541,9 +528,6 @@ static int s6e63m0_prepare(struct drm_panel *panel)
struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
int ret;
 
-   if (ctx->prepared)
-   return 0;
-
ret = s6e63m0_power_on(ctx);
if (ret < 0)
return ret;
@@ -564,8 +548,6 @@ static int s6e63m0_prepare(struct drm_panel *panel)
if (ret < 0)
s6e63m0_unprepare(panel);
 
-   ctx->prepared = true;
-
return ret;
 }
 
@@ -573,9 +555,6 @@ static int s6e63m0_enable(struct drm_panel *panel)
 {
struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 
-   if (ctx->enabled)
-   return 0;
-
s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
msleep(120);
s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_ON);
@@ -588,8 +567,6 @@ static int s6e63m0_enable(struct drm_panel *panel)
 
backlight_enable(ctx->bl_dev);
 
-   ctx->enabled = true;
-
return 0;
 }
 
@@ -709,8 +686,6 @@ int s6e63m0_probe(struct device *dev, void *trsp,
dev_set_drvdata(dev, ctx);
 
ctx->dev = dev;
-   ctx->enabled = false;
-   ctx->prepared = false;
 
ret = device_property_read_u32(dev, "max-brightness", _brightness);
if (ret)
-- 
2.41.0.585.gd2178a4bd4-goog