From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Date: Tue, 24 Jul 2018 14:38:44 +0000 Subject: Re: [PATCH] fbdev: Distinguish between interlaced and progressive modes Message-Id: <1576014.4cjCWdVE3G@amdc3058> List-Id: References: <1828178.vF6XXv5T2I@amdc3058> <20180704190846.GC2701@localhost.localdomain> In-Reply-To: <20180704190846.GC2701@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Fredrik Noring Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, "Maciej W. Rozycki" On Wednesday, July 04, 2018 09:08:48 PM Fredrik Noring wrote: > Hi Bartlomiej, > > > > With this change fb_find_mode can match interlaced and progressive > > > modes equally well, and distinguish between for example 1920x1080i > > > and 1920x1080p. > > > > > > Signed-off-by: Fredrik Noring > > > > Could you please give some examples of use cases that need this change > > (i.e. which fbdev drivers need it for which modes etc.)? > > I discovered the problem when developing a frame buffer driver for the > PlayStation 2 (not yet merged), using the following video modes for the > PlayStation 3 in drivers/video/fbdev/ps3fb.c: > > }, { > /* 1080if */ > "1080if", 50, 1920, 1080, 13468, 148, 484, 36, 4, 88, 5, > FB_SYNC_BROADCAST, FB_VMODE_INTERLACED > }, { > /* 1080pf */ > "1080pf", 50, 1920, 1080, 6734, 148, 484, 36, 4, 88, 5, > FB_SYNC_BROADCAST, FB_VMODE_NONINTERLACED > }, > > In ps3fb_probe, the mode_option module parameter is used with fb_find_mode > but it can only select the interlaced variant of 1920x1080 since the loop > matching the modes does not take the difference between interlaced and > progressive modes into account. > > In short, without the patch, progressive 1920x1080 cannot be chosen as a > mode_option parameter since fb_find_mode (falsely) thinks interlace is a > perfect match. Patch queued for 4.19 (with the above explanation used as patch description), thanks! Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics