Hi Thierry, On Tue, Apr 22, 2014 at 2:03 PM, Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > On Tue, Apr 22, 2014 at 04:09:13AM +0530, Ajay Kumar wrote: >> Register exynos_dp_panel before the list of exynos crtcs and >> connectors are probed. >> >> This is needed because exynos_dp_panel should be registered to >> the drm_panel list via panel-exynos-dp probe, i.e much before >> exynos_dp_bind calls of_drm_find_panel(). >> >> Signed-off-by: Ajay Kumar <ajaykumar.rs@xxxxxxxxxxx> >> --- >> Changes since V1: >> Added platform_driver_unregister(&exynos_dp_panel_driver) to >> exynos_drm_platform_remove as per Jingoo Han's correction >> >> drivers/gpu/drm/exynos/exynos_drm_drv.c | 15 +++++++++++++++ >> drivers/gpu/drm/exynos/exynos_drm_drv.h | 1 + >> 2 files changed, 16 insertions(+) >> >> diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c >> index 1d653f8..2db7f67 100644 >> --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c >> +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c >> @@ -530,12 +530,23 @@ static int exynos_drm_platform_probe(struct platform_device *pdev) >> goto err_unregister_ipp_drv; >> #endif >> >> +#ifdef CONFIG_DRM_PANEL_EXYNOS_DP >> + ret = platform_driver_register(&exynos_dp_panel_driver); >> + if (ret < 0) >> + goto err_unregister_dp_panel; >> +#endif > > No, this is not how you're supposed to use DRM panel drivers. The idea > is that you write a standalone driver for a given panel. > > What you do here has a number of problems. For one it's a driver that's > tightly coupled to Exynos SoCs. But if I have a different SoC that uses > the same panel I want to be able to use the same driver, and not have to > rewrite the driver for my SoC. > > Another problem is that you're assuming here that the driver is built in > and it will break if you try to build either Exynos DRM or the panel > driver as a module. This is perhaps nothing you care about right now, > but eventually people will want to ship a single kernel that can run on > a number of SoCs. But if we keep adding things like this, that kernel > will keep growing in size until it no longer fits in any kind of memory. > > Thierry I completely agree with you in this! Yes, this is not acceptable, but I want to know an "acceptable" workaround for the situation below: I register the driver using module_init(). And, exynos_drm gets probed much before the panel driver probe happens. So, the panel driver hasn't probed yet, but exynos_dp via exynos_drm tries to call "of_drm_find_panel" which always returns NULL. Thanks and regards, Ajay Kumar -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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