On 2016-09-25 23:04, Meng Yi wrote: >> On Wed, Sep 21, 2016 at 11:10:11AM -0700, Stefan Agner wrote: >> > On 2016-09-13 01:49, Meng Yi wrote: >> > >> > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig >> > >> > b/drivers/gpu/drm/fsl-dcu/Kconfig index 14a72c4..f9c76b1 100644 >> > >> > --- a/drivers/gpu/drm/fsl-dcu/Kconfig >> > >> > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig >> > >> > @@ -11,3 +11,9 @@ config DRM_FSL_DCU >> > >> > help >> > >> > Choose this option if you have an Freescale DCU chipset. >> > >> > If M is selected the module will be called fsl-dcu-drm. >> > >> > + >> > >> > +config DRM_FSL_DCU_GAMMA >> > >> > + bool "Gamma Correction Support for NXP/Freescale DCU" >> > >> > + depends on DRM_FSL_DCU >> > >> > + help >> > >> > + Enable support for gamma correction. >> > >> >> > >> What is the reason for making this a configuration option? Are >> > >> there implementation without support for the Gamma tables? >> > >> >> > > When gamma correction is enabled, the color won't display normally >> > > since The gamma tables are not filled with correct data. So I give a >> > > choice to not using The gamma correction when you don't want to use >> > > it. >> > > >> > > Should I remove this configuration? >> > >> > Yeah making this a compile time configuration seems wrong to me. >> > >> > I guess we should fill the table with a reasonable default then. The >> > omapdrm driver seems to do something similar. >> >> Yup Kconfig is definitely not the correct way to fix a setup problem in your >> driver. Note that even when you enable gamma lut userspace is allowed to set >> a NULL table, and in that case you need to either disable the gamma lut, or fill it >> with a 1:1 mapping (if you hw doesn't have a disable flag). At boot-up the table >> will also be NULL (except when you have special setup code), and if that results >> in a black screen your driver is buggy. Papering over a driver bug with Kconfig is >> definitely not ok. > > How about initialize the tables with static array(such as gmma = 2.2, etc) The hardware allows to disable gamma, so I would rather prefer to only enable it when a valid table is set, and disable gamma at startup and when a NULL table is set. This also makes sure what we get the least interference with what we are doing now. -- Stefan _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
