From: Greg Kroah-Hartman Date: Mon, 21 Jan 2019 12:25:03 +0000 (+0100) Subject: 4.4-stable patches X-Git-Tag: v4.20.4~15 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=979c2408515d71d4f6c9872e2e5ef00b3e4097cd;p=thirdparty%2Fkernel%2Fstable-queue.git 4.4-stable patches added patches: drm-fb-helper-ignore-the-value-of-fb_var_screeninfo.pixclock.patch --- diff --git a/queue-4.4/drm-fb-helper-ignore-the-value-of-fb_var_screeninfo.pixclock.patch b/queue-4.4/drm-fb-helper-ignore-the-value-of-fb_var_screeninfo.pixclock.patch new file mode 100644 index 00000000000..e98cbcb9a12 --- /dev/null +++ b/queue-4.4/drm-fb-helper-ignore-the-value-of-fb_var_screeninfo.pixclock.patch @@ -0,0 +1,81 @@ +From 66a8d5bfb518f9f12d47e1d2dce1732279f9451e Mon Sep 17 00:00:00 2001 +From: Ivan Mironov +Date: Tue, 8 Jan 2019 12:23:53 +0500 +Subject: drm/fb-helper: Ignore the value of fb_var_screeninfo.pixclock + +From: Ivan Mironov + +commit 66a8d5bfb518f9f12d47e1d2dce1732279f9451e upstream. + +Strict requirement of pixclock to be zero breaks support of SDL 1.2 +which contains hardcoded table of supported video modes with non-zero +pixclock values[1]. + +To better understand which pixclock values are considered valid and how +driver should handle these values, I briefly examined few existing fbdev +drivers and documentation in Documentation/fb/. And it looks like there +are no strict rules on that and actual behaviour varies: + + * some drivers treat (pixclock == 0) as "use defaults" (uvesafb.c); + * some treat (pixclock == 0) as invalid value which leads to + -EINVAL (clps711x-fb.c); + * some pass converted pixclock value to hardware (uvesafb.c); + * some are trying to find nearest value from predefined table + (vga16fb.c, video_gx.c). + +Given this, I believe that it should be safe to just ignore this value if +changing is not supported. It seems that any portable fbdev application +which was not written only for one specific device working under one +specific kernel version should not rely on any particular behaviour of +pixclock anyway. + +However, while enabling SDL1 applications to work out of the box when +there is no /etc/fb.modes with valid settings, this change affects the +video mode choosing logic in SDL. Depending on current screen +resolution, contents of /etc/fb.modes and resolution requested by +application, this may lead to user-visible difference (not always): +image will be displayed in a right way, but it will be aligned to the +left instead of center. There is no "right behaviour" here as well, as +emulated fbdev, opposing to old fbdev drivers, simply ignores any +requsts of video mode changes with resolutions smaller than current. + +The easiest way to reproduce this problem is to install sdl-sopwith[2], +remove /etc/fb.modes file if it exists, and then try to run sopwith +from console without X. At least in Fedora 29, sopwith may be simply +installed from standard repositories. + +[1] SDL 1.2.15 source code, src/video/fbcon/SDL_fbvideo.c, vesa_timings +[2] http://sdl-sopwith.sourceforge.net/ + +Signed-off-by: Ivan Mironov +Cc: stable@vger.kernel.org +Fixes: 79e539453b34e ("DRM: i915: add mode setting support") +Fixes: 771fe6b912fca ("drm/radeon: introduce kernel modesetting for radeon hardware") +Fixes: 785b93ef8c309 ("drm/kms: move driver specific fb common code to helper functions (v2)") +Signed-off-by: Daniel Vetter +Link: https://patchwork.freedesktop.org/patch/msgid/20190108072353.28078-3-mironov.ivan@gmail.com +Signed-off-by: Greg Kroah-Hartman + + +--- + drivers/gpu/drm/drm_fb_helper.c | 7 ++++++- + 1 file changed, 6 insertions(+), 1 deletion(-) + +--- a/drivers/gpu/drm/drm_fb_helper.c ++++ b/drivers/gpu/drm/drm_fb_helper.c +@@ -1109,9 +1109,14 @@ int drm_fb_helper_check_var(struct fb_va + struct drm_framebuffer *fb = fb_helper->fb; + int depth; + +- if (var->pixclock != 0 || in_dbg_master()) ++ if (in_dbg_master()) + return -EINVAL; + ++ if (var->pixclock != 0) { ++ DRM_DEBUG("fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n"); ++ var->pixclock = 0; ++ } ++ + /* Need to resize the fb object !!! */ + if (var->bits_per_pixel > fb->bits_per_pixel || + var->xres > fb->width || var->yres > fb->height || diff --git a/queue-4.4/series b/queue-4.4/series index d420fb63d33..33fad5805dc 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -68,3 +68,4 @@ block-loop-use-global-lock-for-ioctl-operation.patch loop-fold-__loop_release-into-loop_release.patch loop-get-rid-of-loop_index_mutex.patch loop-fix-double-mutex_unlock-loop_ctl_mutex-in-loop_control_ioctl.patch +drm-fb-helper-ignore-the-value-of-fb_var_screeninfo.pixclock.patch