From: Liviu Dudau liviu.dudau@arm.com Date: 2020-04-24 19:09:50 To: Bernard Zhao bernard@vivo.com Cc: Brian Starkey brian.starkey@arm.com,David Airlie airlied@linux.ie,Daniel Vetter daniel@ffwll.ch,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org,opensource.kernel@vivo.com Subject: Re: [PATCH v2] drm/arm: fixes pixel clock enabled with wrong format>Hi Bernand,
On Thu, Apr 23, 2020 at 11:35:51PM -0700, Bernard Zhao wrote:
The pixel clock is still enabled when the format is wrong. no error branch handle, and also some register is not set in this case, e.g: HDLCD_REG_<color>_SELECT. Maybe we should disable this clock and throw an warn message when this happened. With this change, the code maybe a bit more readable.
Signed-off-by: Bernard Zhao bernard@vivo.com
Changes since V1: *add format error handle, if format is not correct, throw an warning message and disable this clock.
Link for V1:
*https://lore.kernel.org/patchwork/patch/1228501/
drivers/gpu/drm/arm/hdlcd_crtc.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/arm/hdlcd_crtc.c b/drivers/gpu/drm/arm/hdlcd_crtc.c index af67fefed38d..f3945dee2b7d 100644 --- a/drivers/gpu/drm/arm/hdlcd_crtc.c +++ b/drivers/gpu/drm/arm/hdlcd_crtc.c @@ -96,7 +96,7 @@ static int hdlcd_set_pxl_fmt(struct drm_crtc *crtc) }
if (WARN_ON(!format))
return 0;
return -EINVAL;That is the right fix!
/* HDLCD uses 'bytes per pixel', zero means 1 byte */ btpp = (format->bits_per_pixel + 7) / 8; @@ -125,7 +125,7 @@ static int hdlcd_set_pxl_fmt(struct drm_crtc *crtc) return 0; }
-static void hdlcd_crtc_mode_set_nofb(struct drm_crtc *crtc) +static int hdlcd_crtc_mode_set_nofb(struct drm_crtc *crtc)
But this is not. We don't need to propagate the error further, just ....
{ struct hdlcd_drm_private *hdlcd = crtc_to_hdlcd_priv(crtc); struct drm_display_mode *m = &crtc->state->adjusted_mode; @@ -162,9 +162,10 @@ static void hdlcd_crtc_mode_set_nofb(struct drm_crtc *crtc)
err = hdlcd_set_pxl_fmt(crtc); if (err)
return;My previous understanding was that when such an exception occurred, it was caught
in the atomic_enable interface, and then disable pixel clock. I am not sure is this ok or i have to do more register clean operaction.
... return here so that we don't call clk_set_rate();
And for this part, i am a little confused : 1 clk_set_rate must be set even if format is wrong? 2 The original code logic shows that If format is not correct, we will not set registers HDLCD_REG_PIXEL_FORMAT & HDLCD_REG_<color>_SELECT, will this bring in any problems? 3 if 1 the rate must set & 2 registers above doesn`t matter, then maybe there is no need to disable pixel clock.
Regards, Bernard
- return err; >> >> clk_set_rate(hdlcd->clk, m->crtc_clock * 1000); >> + return 0; >> } >> >> static void hdlcd_crtc_atomic_enable(struct drm_crtc *crtc, >> @@ -173,7 +174,11 @@ static void hdlcd_crtc_atomic_enable(struct drm_crtc *crtc, >> struct hdlcd_drm_private *hdlcd = crtc_to_hdlcd_priv(crtc); >> >> clk_prepare_enable(hdlcd->clk); >> - hdlcd_crtc_mode_set_nofb(crtc); >> + if (hdlcd_crtc_mode_set_nofb(crtc)) { >> + DRM_DEBUG_KMS("Invalid format, pixel clock enable failed!\n"); >> + clk_disable_unprepare(hdlcd->clk); >> + return; >> + } >> hdlcd_write(hdlcd, HDLCD_REG_COMMAND, 1); >> drm_crtc_vblank_on(crtc); >> } >> -- >> 2.26.2 >> > >-- >==================== >| I would like to | >| fix the world, | >| but they're not | >| giving me the | > \ source code! / > --------------- > ¯_(ツ)_/¯