2023-05-08 05:59:55

by Liu Ying

Subject: [PATCH v5 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

A valid bridge is already found in lcdif_attach_bridge() and set
to lcdif->bridge, so lcdif->bridge cannot be a NULL pointer. Drop
the unnecessary NULL pointer check in KMS stage.

Tested-by: Alexander Stein <[email protected]>
Reviewed-by: Alexander Stein <[email protected]>
Signed-off-by: Liu Ying <[email protected]>
---
v4->v5:
* Add Alexander's T-b tag.

v3->v4:
* Add Alexander's R-b tag.

v2->v3:
* No change.

v1->v2:
* Split from patch 2/2 in v1. (Marek, Alexander)

drivers/gpu/drm/mxsfb/lcdif_kms.c | 33 +++++++++++--------------------
1 file changed, 12 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
index 262bc43b1079..e54200a9fcb9 100644
--- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
+++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
@@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
u32 bus_flags = 0;

- if (lcdif->bridge && lcdif->bridge->timings)
+ if (lcdif->bridge->timings)
bus_flags = lcdif->bridge->timings->input_bus_flags;
else if (bridge_state)
bus_flags = bridge_state->input_bus_cfg.flags;
@@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc *crtc,
struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
struct drm_bridge_state *bridge_state = NULL;
struct drm_device *drm = lcdif->drm;
- u32 bus_format = 0;
+ u32 bus_format;
dma_addr_t paddr;

- /* If there is a bridge attached to the LCDIF, use its bus format */
- if (lcdif->bridge) {
- bridge_state =
- drm_atomic_get_new_bridge_state(state,
- lcdif->bridge);
- if (!bridge_state)
- bus_format = MEDIA_BUS_FMT_FIXED;
- else
- bus_format = bridge_state->input_bus_cfg.format;
-
- if (bus_format == MEDIA_BUS_FMT_FIXED) {
- dev_warn_once(drm->dev,
- "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
- "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
- bus_format = MEDIA_BUS_FMT_RGB888_1X24;
- }
- }
+ bridge_state = drm_atomic_get_new_bridge_state(state, lcdif->bridge);
+ if (!bridge_state)
+ bus_format = MEDIA_BUS_FMT_FIXED;
+ else
+ bus_format = bridge_state->input_bus_cfg.format;

- /* If all else fails, default to RGB888_1X24 */
- if (!bus_format)
+ if (bus_format == MEDIA_BUS_FMT_FIXED) {
+ dev_warn_once(drm->dev,
+ "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
+ "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+ }

clk_set_rate(lcdif->clk, m->crtc_clock * 1000);

--
2.37.1

2023-05-09 02:19:32

by Marek Vasut

Subject: Re: [PATCH v5 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

On 5/8/23 07:57, Liu Ying wrote:

Hi,

> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> index 262bc43b1079..e54200a9fcb9 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
> struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> u32 bus_flags = 0;
>
> - if (lcdif->bridge && lcdif->bridge->timings)
> + if (lcdif->bridge->timings)
> bus_flags = lcdif->bridge->timings->input_bus_flags;
> else if (bridge_state)
> bus_flags = bridge_state->input_bus_cfg.flags;
> @@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc *crtc,
> struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> struct drm_bridge_state *bridge_state = NULL;
> struct drm_device *drm = lcdif->drm;
> - u32 bus_format = 0;
> + u32 bus_format;
> dma_addr_t paddr;
>
> - /* If there is a bridge attached to the LCDIF, use its bus format */
> - if (lcdif->bridge) {
> - bridge_state =
> - drm_atomic_get_new_bridge_state(state,
> - lcdif->bridge);
> - if (!bridge_state)
> - bus_format = MEDIA_BUS_FMT_FIXED;
> - else
> - bus_format = bridge_state->input_bus_cfg.format;
> -
> - if (bus_format == MEDIA_BUS_FMT_FIXED) {
> - dev_warn_once(drm->dev,
> - "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
> - "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
> - bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> - }
> - }
> + bridge_state = drm_atomic_get_new_bridge_state(state, lcdif->bridge);
> + if (!bridge_state)
> + bus_format = MEDIA_BUS_FMT_FIXED;
> + else
> + bus_format = bridge_state->input_bus_cfg.format;

The code below seems to change the logic slightly.

Could it happen that:
- bridge_state is valid (i.e. non-NULL)
- bridge_state->input_bus_cfg.format is set to 0 (i.e. not set) ?
(note that MEDIA_BUS_FMT_FIXED is defined as 0x0001)

> - /* If all else fails, default to RGB888_1X24 */
> - if (!bus_format)
> + if (bus_format == MEDIA_BUS_FMT_FIXED) {
> + dev_warn_once(drm->dev,
> + "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
> + "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
> bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> + }
>
> clk_set_rate(lcdif->clk, m->crtc_clock * 1000);

[...]

2023-05-10 08:48:16

by Ying Liu

Subject: Re: [PATCH v5 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

On Tue, May 9, 2023 at 10:14 AM Marek Vasut <[email protected]> wrote:
>
> On 5/8/23 07:57, Liu Ying wrote:
>
> Hi,

Hi,

>
> > diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > index 262bc43b1079..e54200a9fcb9 100644
> > --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > @@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
> > struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> > u32 bus_flags = 0;
> >
> > - if (lcdif->bridge && lcdif->bridge->timings)
> > + if (lcdif->bridge->timings)
> > bus_flags = lcdif->bridge->timings->input_bus_flags;
> > else if (bridge_state)
> > bus_flags = bridge_state->input_bus_cfg.flags;
> > @@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc *crtc,
> > struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> > struct drm_bridge_state *bridge_state = NULL;
> > struct drm_device *drm = lcdif->drm;
> > - u32 bus_format = 0;
> > + u32 bus_format;
> > dma_addr_t paddr;
> >
> > - /* If there is a bridge attached to the LCDIF, use its bus format */
> > - if (lcdif->bridge) {
> > - bridge_state =
> > - drm_atomic_get_new_bridge_state(state,
> > - lcdif->bridge);
> > - if (!bridge_state)
> > - bus_format = MEDIA_BUS_FMT_FIXED;
> > - else
> > - bus_format = bridge_state->input_bus_cfg.format;
> > -
> > - if (bus_format == MEDIA_BUS_FMT_FIXED) {
> > - dev_warn_once(drm->dev,
> > - "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
> > - "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
> > - bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> > - }
> > - }
> > + bridge_state = drm_atomic_get_new_bridge_state(state, lcdif->bridge);
> > + if (!bridge_state)
> > + bus_format = MEDIA_BUS_FMT_FIXED;
> > + else
> > + bus_format = bridge_state->input_bus_cfg.format;
>
> The code below seems to change the logic slightly.
>
> Could it happen that:
> - bridge_state is valid (i.e. non-NULL)
> - bridge_state->input_bus_cfg.format is set to 0 (i.e. not set) ?
> (note that MEDIA_BUS_FMT_FIXED is defined as 0x0001)

Yes, bridge_state->input_bus_cfg.format could be zero.
Will keep the below default MEDIA_BUS_FMT_RGB888_1X24
bus format setting in next version.

Regards,
Liu Ying

>
> > - /* If all else fails, default to RGB888_1X24 */
> > - if (!bus_format)
> > + if (bus_format == MEDIA_BUS_FMT_FIXED) {
> > + dev_warn_once(drm->dev,
> > + "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
> > + "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
> > bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> > + }
> >
> > clk_set_rate(lcdif->clk, m->crtc_clock * 1000);
>
> [...]

2023-05-10 09:15:55

by Marek Vasut

Subject: Re: [PATCH v5 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

On 5/10/23 10:30, Ying Liu wrote:
> On Tue, May 9, 2023 at 10:14 AM Marek Vasut <[email protected]> wrote:
>>
>> On 5/8/23 07:57, Liu Ying wrote:
>>
>> Hi,
>
> Hi,

Hi,

>>> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
>>> index 262bc43b1079..e54200a9fcb9 100644
>>> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
>>> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
>>> @@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
>>> struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
>>> u32 bus_flags = 0;
>>>
>>> - if (lcdif->bridge && lcdif->bridge->timings)
>>> + if (lcdif->bridge->timings)
>>> bus_flags = lcdif->bridge->timings->input_bus_flags;
>>> else if (bridge_state)
>>> bus_flags = bridge_state->input_bus_cfg.flags;
>>> @@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc *crtc,
>>> struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
>>> struct drm_bridge_state *bridge_state = NULL;
>>> struct drm_device *drm = lcdif->drm;
>>> - u32 bus_format = 0;
>>> + u32 bus_format;
>>> dma_addr_t paddr;
>>>
>>> - /* If there is a bridge attached to the LCDIF, use its bus format */
>>> - if (lcdif->bridge) {
>>> - bridge_state =
>>> - drm_atomic_get_new_bridge_state(state,
>>> - lcdif->bridge);
>>> - if (!bridge_state)
>>> - bus_format = MEDIA_BUS_FMT_FIXED;
>>> - else
>>> - bus_format = bridge_state->input_bus_cfg.format;
>>> -
>>> - if (bus_format == MEDIA_BUS_FMT_FIXED) {
>>> - dev_warn_once(drm->dev,
>>> - "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
>>> - "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
>>> - bus_format = MEDIA_BUS_FMT_RGB888_1X24;
>>> - }
>>> - }
>>> + bridge_state = drm_atomic_get_new_bridge_state(state, lcdif->bridge);
>>> + if (!bridge_state)
>>> + bus_format = MEDIA_BUS_FMT_FIXED;
>>> + else
>>> + bus_format = bridge_state->input_bus_cfg.format;
>>
>> The code below seems to change the logic slightly.
>>
>> Could it happen that:
>> - bridge_state is valid (i.e. non-NULL)
>> - bridge_state->input_bus_cfg.format is set to 0 (i.e. not set) ?
>> (note that MEDIA_BUS_FMT_FIXED is defined as 0x0001)
>
> Yes, bridge_state->input_bus_cfg.format could be zero.
> Will keep the below default MEDIA_BUS_FMT_RGB888_1X24
> bus format setting in next version.

Thanks for confirming.

The rest of the series looks good, sorry for the delay in reviews.