2015-02-21 16:18 GMT+01:00 Fabio Estevam <festevam@xxxxxxxxx>: > > Hi, > > Carlos Soto uses a Karo mx25 and he noticed that the LCD only works if we do: > > echo 1 > /sys/class/graphics/fb0/blank > echo 0 > /sys/class/graphics/fb0/blank > > I can confirm the same on mx25pdk running 3.19 [1], but I could not > understand why the display does not start turned on by default. > > [1] http://www.spinics.net/lists/arm-kernel/msg399949.html > > Any ideas? > > Thanks, > > Fabio Estevam Hi, I know it's been a long time since Fabio posted the issue but recently I had some time to work on it again, and I've narrowed it down a little. The problem seems to be related to the IPG clock used by the iMX25 framebuffer. All clocks used by the fb are enabled in imxfb_enable_controller(...) ... clk_prepare_enable(fbi->clk_ipg); clk_prepare_enable(fbi->clk_ahb); clk_prepare_enable(fbi->clk_per); fbi->enabled = true; ... But if the IPG clock is disabled and enabled right after, the LCD works fine. The changes made in imxfb.c were: ... clk_prepare_enable(fbi->clk_ipg); clk_disable_unprepare(fbi->clk_ipg); clk_prepare_enable(fbi->clk_ipg); clk_prepare_enable(fbi->clk_ahb); clk_prepare_enable(fbi->clk_per); fbi->enabled = true; ... It was suggested by Fabio that this could be caused by a wrong clock reference count which prevented the IPG fb clock to be enabled, but I've checked in debugfs, and both enable_cnt and prepare_cnt seem OK for all three FB clocks. So, I'm really stuck here. Any hints would be greatly appreciated. Thanks, Carlos Soto 2015-02-21 16:18 GMT+01:00 Fabio Estevam <festevam@xxxxxxxxx>: > Hi, > > Carlos Soto uses a Karo mx25 and he noticed that the LCD only works if we do: > > echo 1 > /sys/class/graphics/fb0/blank > echo 0 > /sys/class/graphics/fb0/blank > > I can confirm the same on mx25pdk running 3.19 [1], but I could not > understand why the display does not start turned on by default. > > [1] http://www.spinics.net/lists/arm-kernel/msg399949.html > > Any ideas? > > Thanks, > > Fabio Estevam -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
