Re: [PATCH 1/4] OMAPDSS: Fix DSS clock multiplier issue on 3703 and probably 3630
From: Tomi Valkeinen <hidden>
Date: 2014-05-09 07:38:54
Also in:
linux-arm-kernel, linux-devicetree, linux-omap
On 30/04/14 02:52, Tony Lindgren wrote:
Otherwise we can get often errors like the following and the display won't come on: omapdss APPLY error: FIFO UNDERFLOW on gfx, disabling the overlay omapdss APPLY error: SYNC_LOST on channel lcd, restarting the output with video overlays disabled There are some earlier references to this issue: http://www.spinics.net/lists/linux-omap/msg59511.html http://www.spinics.net/lists/linux-omap/msg59724.html
Those don't sound like the same issue, but it's hard to say. What kind of clock rates do you get? Cat you paste debugfs/omapdss/clk, with and without this patch? What resolution do you have? If it's a very high resolution (say, DVI output to a monitor), it could just be an issue of not-enough-memory-bandwidth.
quoted hunk ↗ jump to hunk
It seems that it's safe to set the lower values even for 3630. If we can confirm that 3630 works with the higher values reliably we can add further detection. Signed-off-by: Tony Lindgren <tony@atomide.com> --- drivers/video/fbdev/omap2/dss/dss.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/drivers/video/fbdev/omap2/dss/dss.c b/drivers/video/fbdev/omap2/dss/dss.c index d55266c..ad6561f 100644 --- a/drivers/video/fbdev/omap2/dss/dss.c +++ b/drivers/video/fbdev/omap2/dss/dss.c@@ -707,9 +707,10 @@ static const struct dss_features omap34xx_dss_feats __initconst = { .dpi_select_source = &dss_dpi_select_source_omap2_omap3, }; +/* Supposedly 3630 can use div 32 mult 2, but that needs to be rechecked */ static const struct dss_features omap3630_dss_feats __initconst = { - .fck_div_max = 32, - .dss_fck_multiplier = 1, + .fck_div_max = 16, + .dss_fck_multiplier = 2,
These values tell about the clock hardware, they are not settings that can be changed to change the clock. OMAP3630 has a fixed x2 multiplier and a divider with maximum value of 16. Tomi
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