| Message ID | 075ffb50cc16ab055b5d47b30163401bb356ab51.1487175046.git-series.maxime.ripard@free-electrons.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Maxime, sorry, I have missed the discussion about the double buffering/virtual surface size patch series two weeks ago. My comments about the patch are inline: On Wed, Feb 15, 2017 at 05:19:08PM +0100, Maxime Ripard wrote: > From: Xinliang Liu <xinliang.liu@linaro.org> Mabye you should take the authorship here. Taking the credit and the blame, because the patch was heavily modified by you and me. But I don't really know what the offical police about that is. > > This patch add a config to support to create multi buffer for cma fbdev. > Such as double buffer and triple buffer. > > Cma fbdev is convient to add a legency fbdev. And still many Android > devices use fbdev now and at least double buffer is needed for these > Android devices, so that a buffer flip can be operated. It will need > some time for Android device vendors to abondon legency fbdev. So multi > buffer for fbdev is needed. > > Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org> > [s.christ@phytec.de: Picking patch from > https://lkml.org/lkml/2015/9/14/188] > Signed-off-by: Stefan Christ <s.christ@phytec.de> > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Reviewed-by: Stefan Lengfeld <contact@stefanchrist.eu> My surname has changed from "Christ" to "Lengfeld" recently. So my review tag contains the new name. > --- > drivers/gpu/drm/Kconfig | 9 +++++++++ > drivers/gpu/drm/drm_fb_helper.c | 10 ++++++++++ > 2 files changed, 19 insertions(+), 0 deletions(-) > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index ebfe8404c25f..700c8b8e57a9 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -84,6 +84,15 @@ config DRM_FBDEV_EMULATION > > If in doubt, say "Y". > > +config DRM_FBDEV_OVERALLOC > + int "Overallocation of the fbdev buffer" > + depends on DRM_FBDEV_EMULATION > + default 100 > + help > + Defines the fbdev buffer overallocation in percent. Default > + is 100. Typical values for double buffering will be 200, > + triple buffering 300. > + > config DRM_LOAD_EDID_FIRMWARE > bool "Allow to specify an EDID data set instead of probing for it" > depends on DRM_KMS_HELPER > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index e934b541feea..c6de87abaca8 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -48,6 +48,12 @@ module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); > MODULE_PARM_DESC(fbdev_emulation, > "Enable legacy fbdev emulation [default=true]"); > > +static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC; > +module_param(drm_fbdev_overalloc, int, 0444); Maybe the variable should be of type "uint" instead of "int". This would rule out the negative numbers error case. > +MODULE_PARM_DESC(drm_fbdev_overalloc, > + "Overallocation of the fbdev buffer (%) [default=" > + __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); > + > static LIST_HEAD(kernel_fb_helper_list); > static DEFINE_MUTEX(kernel_fb_helper_lock); > > @@ -1573,6 +1579,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, > sizes.fb_height = sizes.surface_height = 768; > } > > + /* Handle our overallocation */ > + sizes.surface_height *= drm_fbdev_overalloc; > + sizes.surface_height /= 100; > + The code can trigger an arithmetic overflow, but I think we can ignore this error case here. But there should be a check for drm_fbdev_overalloc not be smaller than 100. If it is smaller, the variable drm_fbdev_overalloc should have the default value "100". Otherwise the virtual surface height can be smaller than the physical height. This could trigger a lot of errors in existing code paths. Kind regards, Stefan Lengfeld > /* push down into drivers */ > ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes); > if (ret < 0) > -- > git-series 0.8.11 > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
Hi Stefan, On Mon, Feb 20, 2017 at 06:07:10PM +0100, Stefan Lengfeld wrote: > Hi Maxime, > > sorry, I have missed the discussion about the double buffering/virtual > surface size patch series two weeks ago. My comments about the patch are > inline: > > On Wed, Feb 15, 2017 at 05:19:08PM +0100, Maxime Ripard wrote: > > From: Xinliang Liu <xinliang.liu@linaro.org> > > Mabye you should take the authorship here. Taking the credit and the > blame, because the patch was heavily modified by you and me. But I don't > really know what the offical police about that is. I don't usually know when to do that as well. But yeah, you're probably right. > > > > This patch add a config to support to create multi buffer for cma fbdev. > > Such as double buffer and triple buffer. > > > > Cma fbdev is convient to add a legency fbdev. And still many Android > > devices use fbdev now and at least double buffer is needed for these > > Android devices, so that a buffer flip can be operated. It will need > > some time for Android device vendors to abondon legency fbdev. So multi > > buffer for fbdev is needed. > > > > Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org> > > [s.christ@phytec.de: Picking patch from > > https://lkml.org/lkml/2015/9/14/188] > > Signed-off-by: Stefan Christ <s.christ@phytec.de> > > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> > > Reviewed-by: Stefan Lengfeld <contact@stefanchrist.eu> > > My surname has changed from "Christ" to "Lengfeld" recently. So my > review tag contains the new name. Ack > > > --- > > drivers/gpu/drm/Kconfig | 9 +++++++++ > > drivers/gpu/drm/drm_fb_helper.c | 10 ++++++++++ > > 2 files changed, 19 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > > index ebfe8404c25f..700c8b8e57a9 100644 > > --- a/drivers/gpu/drm/Kconfig > > +++ b/drivers/gpu/drm/Kconfig > > @@ -84,6 +84,15 @@ config DRM_FBDEV_EMULATION > > > > If in doubt, say "Y". > > > > +config DRM_FBDEV_OVERALLOC > > + int "Overallocation of the fbdev buffer" > > + depends on DRM_FBDEV_EMULATION > > + default 100 > > + help > > + Defines the fbdev buffer overallocation in percent. Default > > + is 100. Typical values for double buffering will be 200, > > + triple buffering 300. > > + > > config DRM_LOAD_EDID_FIRMWARE > > bool "Allow to specify an EDID data set instead of probing for it" > > depends on DRM_KMS_HELPER > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > > index e934b541feea..c6de87abaca8 100644 > > --- a/drivers/gpu/drm/drm_fb_helper.c > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > @@ -48,6 +48,12 @@ module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); > > MODULE_PARM_DESC(fbdev_emulation, > > "Enable legacy fbdev emulation [default=true]"); > > > > +static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC; > > +module_param(drm_fbdev_overalloc, int, 0444); > > Maybe the variable should be of type "uint" instead of "int". This would > rule out the negative numbers error case. Yep, I'll change it. > > +MODULE_PARM_DESC(drm_fbdev_overalloc, > > + "Overallocation of the fbdev buffer (%) [default=" > > + __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); > > + > > static LIST_HEAD(kernel_fb_helper_list); > > static DEFINE_MUTEX(kernel_fb_helper_lock); > > > > @@ -1573,6 +1579,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, > > sizes.fb_height = sizes.surface_height = 768; > > } > > > > + /* Handle our overallocation */ > > + sizes.surface_height *= drm_fbdev_overalloc; > > + sizes.surface_height /= 100; > > + > > The code can trigger an arithmetic overflow, but I think we can ignore > this error case here. > > But there should be a check for drm_fbdev_overalloc not be smaller than > 100. If it is smaller, the variable drm_fbdev_overalloc should have the > default value "100". Otherwise the virtual surface height can be smaller > than the physical height. This could trigger a lot of errors in existing > code paths. That's a really good point, I'll change that. Thanks! Maxime
On Wed, Feb 22, 2017 at 04:49:01PM -0800, Maxime Ripard wrote: > Hi Stefan, > > On Mon, Feb 20, 2017 at 06:07:10PM +0100, Stefan Lengfeld wrote: > > Hi Maxime, > > > > sorry, I have missed the discussion about the double buffering/virtual > > surface size patch series two weeks ago. My comments about the patch are > > inline: > > > > On Wed, Feb 15, 2017 at 05:19:08PM +0100, Maxime Ripard wrote: > > > From: Xinliang Liu <xinliang.liu@linaro.org> > > > > Mabye you should take the authorship here. Taking the credit and the > > blame, because the patch was heavily modified by you and me. But I don't > > really know what the offical police about that is. > > I don't usually know when to do that as well. But yeah, you're > probably right. Sob line is the important bit, retaining original authorship is just goodwill, and if in doubt showing more curtesy rarely hurts :-) Patch applied to drm-misc, with Dave's ack after a quick irc discussion. -Daniel > > > > > > > This patch add a config to support to create multi buffer for cma fbdev. > > > Such as double buffer and triple buffer. > > > > > > Cma fbdev is convient to add a legency fbdev. And still many Android > > > devices use fbdev now and at least double buffer is needed for these > > > Android devices, so that a buffer flip can be operated. It will need > > > some time for Android device vendors to abondon legency fbdev. So multi > > > buffer for fbdev is needed. > > > > > > Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org> > > > [s.christ@phytec.de: Picking patch from > > > https://lkml.org/lkml/2015/9/14/188] > > > Signed-off-by: Stefan Christ <s.christ@phytec.de> > > > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> > > > > Reviewed-by: Stefan Lengfeld <contact@stefanchrist.eu> > > > > My surname has changed from "Christ" to "Lengfeld" recently. So my > > review tag contains the new name. > > Ack > > > > > > --- > > > drivers/gpu/drm/Kconfig | 9 +++++++++ > > > drivers/gpu/drm/drm_fb_helper.c | 10 ++++++++++ > > > 2 files changed, 19 insertions(+), 0 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > > > index ebfe8404c25f..700c8b8e57a9 100644 > > > --- a/drivers/gpu/drm/Kconfig > > > +++ b/drivers/gpu/drm/Kconfig > > > @@ -84,6 +84,15 @@ config DRM_FBDEV_EMULATION > > > > > > If in doubt, say "Y". > > > > > > +config DRM_FBDEV_OVERALLOC > > > + int "Overallocation of the fbdev buffer" > > > + depends on DRM_FBDEV_EMULATION > > > + default 100 > > > + help > > > + Defines the fbdev buffer overallocation in percent. Default > > > + is 100. Typical values for double buffering will be 200, > > > + triple buffering 300. > > > + > > > config DRM_LOAD_EDID_FIRMWARE > > > bool "Allow to specify an EDID data set instead of probing for it" > > > depends on DRM_KMS_HELPER > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > > > index e934b541feea..c6de87abaca8 100644 > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > @@ -48,6 +48,12 @@ module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); > > > MODULE_PARM_DESC(fbdev_emulation, > > > "Enable legacy fbdev emulation [default=true]"); > > > > > > +static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC; > > > +module_param(drm_fbdev_overalloc, int, 0444); > > > > Maybe the variable should be of type "uint" instead of "int". This would > > rule out the negative numbers error case. > > Yep, I'll change it. > > > > +MODULE_PARM_DESC(drm_fbdev_overalloc, > > > + "Overallocation of the fbdev buffer (%) [default=" > > > + __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); > > > + > > > static LIST_HEAD(kernel_fb_helper_list); > > > static DEFINE_MUTEX(kernel_fb_helper_lock); > > > > > > @@ -1573,6 +1579,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, > > > sizes.fb_height = sizes.surface_height = 768; > > > } > > > > > > + /* Handle our overallocation */ > > > + sizes.surface_height *= drm_fbdev_overalloc; > > > + sizes.surface_height /= 100; > > > + > > > > The code can trigger an arithmetic overflow, but I think we can ignore > > this error case here. > > > > But there should be a check for drm_fbdev_overalloc not be smaller than > > 100. If it is smaller, the variable drm_fbdev_overalloc should have the > > default value "100". Otherwise the virtual surface height can be smaller > > than the physical height. This could trigger a lot of errors in existing > > code paths. > > That's a really good point, I'll change that. > > Thanks! > Maxime > > -- > Maxime Ripard, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index ebfe8404c25f..700c8b8e57a9 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -84,6 +84,15 @@ config DRM_FBDEV_EMULATION If in doubt, say "Y". +config DRM_FBDEV_OVERALLOC + int "Overallocation of the fbdev buffer" + depends on DRM_FBDEV_EMULATION + default 100 + help + Defines the fbdev buffer overallocation in percent. Default + is 100. Typical values for double buffering will be 200, + triple buffering 300. + config DRM_LOAD_EDID_FIRMWARE bool "Allow to specify an EDID data set instead of probing for it" depends on DRM_KMS_HELPER diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index e934b541feea..c6de87abaca8 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -48,6 +48,12 @@ module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600); MODULE_PARM_DESC(fbdev_emulation, "Enable legacy fbdev emulation [default=true]"); +static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC; +module_param(drm_fbdev_overalloc, int, 0444); +MODULE_PARM_DESC(drm_fbdev_overalloc, + "Overallocation of the fbdev buffer (%) [default=" + __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]"); + static LIST_HEAD(kernel_fb_helper_list); static DEFINE_MUTEX(kernel_fb_helper_lock); @@ -1573,6 +1579,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper, sizes.fb_height = sizes.surface_height = 768; } + /* Handle our overallocation */ + sizes.surface_height *= drm_fbdev_overalloc; + sizes.surface_height /= 100; + /* push down into drivers */ ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes); if (ret < 0)