On Thu, Mar 08, 2012 at 04:31:51PM +0100, Laurent Pinchart wrote: > Hi Joonyoung, > > On Thursday 08 March 2012 22:05:50 Joonyoung Shim wrote: > > On 03/08/2012 08:34 PM, Laurent Pinchart wrote: > > > The fb_videomode structure stores the front porch and back porch in the > > > right_margin and left_margin fields respectively. right_margin should > > > thus be computed with hsync_start - hdisplay, and left_margin with > > > htotal - hsync_end. The same holds for the vertical direction. > > > > > > Active Front Sync Back > > > Region Porch Porch > > > > > > <-------------------><----------------><-------------><----------------> > > > > > > //////////////////| > > > > > > ////////////////// | > > > > > > ////////////////// |.................. .................. > > > > > > _______________ > > > > > > <------ xres -------><- right_margin -><- hsync_len -><- left_margin --> > > > > > > <---- hdisplay -----> > > > <------------ hsync_start ------------> > > > <--------------------- hsync_end --------------------> > > > <--------------------------------- htotal -----------------------------> > > > > > > Fix the fb_videomode<-> drm_mode_modeinfo conversion functions > > > accordingly. > > > > > > Signed-off-by: Laurent Pinchart<laurent.pinchart@xxxxxxxxxxxxxxxx> > > > --- > > > > > > drivers/gpu/drm/exynos/exynos_drm_connector.c | 16 ++++++++-------- > > > 1 files changed, 8 insertions(+), 8 deletions(-) > > > > > > While trying to understand how the fb_videomode and drm_mode_modeinfo > > > fields map to each other, I found what might be a bug in the Exynos DRM > > > driver. Could you please check and confirm that my understanding is > > > correct ? > > > > Good catch. You can refer Documentation/fb/framebuffer.txt to know in > > detail. > > > > Acked-by: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx> > > Thank you. There's a similar issue in exynos_mipi_dsi_set_display_mode() where > front and back porch are inverted. I'll submit a patch for that as well. Damned. This seems to be a common misunderstanding. I never really thought about it and always assumed that 'front porch' and 'back porch' refers to the picture and not to the sync signal. I was so sure that I didn't even care to google it before I saw this patch. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
