From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Date: Wed, 28 Jan 2015 15:42:26 +0100 Subject: [U-Boot] [PATCH v2] sunxi: video: Force h/vsync active high when using ext. vga dac on some boards In-Reply-To: <1422446756.14124.9.camel@hellion.org.uk> References: <1422442041-21957-1-git-send-email-hdegoede@redhat.com> <1422446756.14124.9.camel@hellion.org.uk> Message-ID: <54C8F552.2010204@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 28-01-15 13:05, Ian Campbell wrote: > On Wed, 2015-01-28 at 11:47 +0100, Hans de Goede wrote: >> On both my A13-OLinuxIno and my A13-OLinuxIno-Micro, the vga output gives an >> unstable image when active low v or hsync is used. >> >> The problem seems to be specific to the OLinuxIno A13 (normal & micro) >> boards. I've just looked up the schematics and they use an opendrain driver >> for the vga sync lines, and with sync pulses it is the logical high->low >> edge of the pulse which counts for the timing, which with an active low >> sync is being driven by the pull-up, and that simply seems to not drive >> it hard enough to get a stable image. >> >> So force v and hsync active high on these boards. independent of what the >> modeline says. This fixes the unstable image. >> >> Signed-off-by: Hans de Goede > > Acked-by: Ian Campbell Thanks. > Although I might have been tempted to adjust mode->sync in the caller or > the place which populates it in the first place, just due to a general > dislike of boolean params to functions (which are opaque at the caller) > and to keep mode in sync with reality (if that matters). I had the same idea, but mode can point to the global fixed mode list, so it is: "const struct ctfb_res_modes *mode" and we cannot change what a const pointer points too. Regards, Hans