| Message ID | 20200629235210.441709-6-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,01/10] dt-bindings: display: Convert ingenic, lcd.txt to YAML | expand |
Hi Paul. On Tue, Jun 30, 2020 at 01:52:06AM +0200, Paul Cercueil wrote: > The address of the DMA descriptor never changes. It can therefore be set > in the probe function. > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > --- > > Notes: > v2: No change > > drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c > index 924c8daf071a..f7b0c5dc8cd8 100644 > --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c > +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c > @@ -358,8 +358,6 @@ static void ingenic_drm_crtc_atomic_flush(struct drm_crtc *crtc, > ingenic_drm_crtc_update_ctrl(priv, finfo); > > clk_set_rate(priv->pix_clk, state->adjusted_mode.clock * 1000); > - > - regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc->next); > } > > if (event) { > @@ -757,6 +755,9 @@ static int ingenic_drm_probe(struct platform_device *pdev) > } > } > > + /* Set address of our DMA descriptor chain */ > + regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc_phys); > + What is the purpose of this code after the assignment was moved: static int ingenic_drm_probe(struct platform_device *pdev) { ... priv->dma_hwdesc->next = priv->dma_hwdesc_phys; I do not see ->next used anymore. Could this assignment be dropped? And the following line: priv->dma_hwdesc->id = 0xdeafbead; I can only see ->id be assingned, it is never referenced?? Maybe this is all related to the structure assumed by the data pointed to by JZ_REG_LCD_DA0? Sam > ret = drm_dev_register(drm, 0); > if (ret) { > dev_err(dev, "Failed to register DRM driver\n"); > -- > 2.27.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
Hi Sam, Le mar. 30 juin 2020 à 13:44, Sam Ravnborg <sam@ravnborg.org> a écrit : > Hi Paul. > > On Tue, Jun 30, 2020 at 01:52:06AM +0200, Paul Cercueil wrote: >> The address of the DMA descriptor never changes. It can therefore >> be set >> in the probe function. >> >> Signed-off-by: Paul Cercueil <paul@crapouillou.net> >> --- >> >> Notes: >> v2: No change >> >> drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c >> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c >> index 924c8daf071a..f7b0c5dc8cd8 100644 >> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c >> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c >> @@ -358,8 +358,6 @@ static void >> ingenic_drm_crtc_atomic_flush(struct drm_crtc *crtc, >> ingenic_drm_crtc_update_ctrl(priv, finfo); >> >> clk_set_rate(priv->pix_clk, state->adjusted_mode.clock * 1000); >> - >> - regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc->next); >> } >> >> if (event) { >> @@ -757,6 +755,9 @@ static int ingenic_drm_probe(struct >> platform_device *pdev) >> } >> } >> >> + /* Set address of our DMA descriptor chain */ >> + regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc_phys); >> + > > > What is the purpose of this code after the assignment was moved: > > static int ingenic_drm_probe(struct platform_device *pdev) > { > ... > priv->dma_hwdesc->next = priv->dma_hwdesc_phys; > > I do not see ->next used anymore. > Could this assignment be dropped? > > > And the following line: > priv->dma_hwdesc->id = 0xdeafbead; > > I can only see ->id be assingned, it is never referenced?? > > Maybe this is all related to the structure assumed by the data pointed > to by JZ_REG_LCD_DA0? As its name suggests, 'dma_hwdesc' points to a DMA hardware descriptor. Setting ->next sets the address of the next descriptor (which is itself since we only use one descriptor). The 'id' field will be copied by the hardware to a register when the DMA descriptor is loaded, so we can know from userspace (debugfs) what DMA descriptors are loaded by looking up the IDs. -Paul > Sam > >> ret = drm_dev_register(drm, 0); >> if (ret) { >> dev_err(dev, "Failed to register DRM driver\n"); >> -- >> 2.27.0 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c index 924c8daf071a..f7b0c5dc8cd8 100644 --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c @@ -358,8 +358,6 @@ static void ingenic_drm_crtc_atomic_flush(struct drm_crtc *crtc, ingenic_drm_crtc_update_ctrl(priv, finfo); clk_set_rate(priv->pix_clk, state->adjusted_mode.clock * 1000); - - regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc->next); } if (event) { @@ -757,6 +755,9 @@ static int ingenic_drm_probe(struct platform_device *pdev) } } + /* Set address of our DMA descriptor chain */ + regmap_write(priv->map, JZ_REG_LCD_DA0, priv->dma_hwdesc_phys); + ret = drm_dev_register(drm, 0); if (ret) { dev_err(dev, "Failed to register DRM driver\n");
The address of the DMA descriptor never changes. It can therefore be set in the probe function. Signed-off-by: Paul Cercueil <paul@crapouillou.net> --- Notes: v2: No change drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)