Friday 30 October 2009 18:33:18 Tony Lindgren napisał(a): > * Janusz Krzysztofik <jkrzyszt@xxxxxxxxxxxx> [091030 07:43]: > > Thursday 29 October 2009 23:39:44 Janusz Krzysztofik napisał(a): > > > With CONFIG_PM=y, the omapfb/lcd device on Amstrad Delta, after > > > initially starting correctly, breaks with the following error messages: > > > > > > omapfb omapfb: resetting (status 0xffffff96,reset count 1) > > > ... > > > omapfb omapfb: resetting (status 0xffffff96,reset count 100) > > > omapfb omapfb: too many reset attempts, giving up. > > > > > > Looking closer at this I have found that it had been broken almost 2 > > > years ago with commit 2418996e3b100114edb2ae110d5d4acb928909d2, PM > > > fixes for OMAP1. > > > > > > The definite reason for broken omapfb/lcd_ams_delta in PM mode appeared > > > to be ARM_IDLECT1:IDLIF_ARM (bit 6) put into idle. The patch below > > > fixes it. > > > > > > Since PM area is quite new to me, I am not sure if there may be a > > > better solution. AFAICS, the standard way to prevent an ARM_CLKCT1 bit > > > being switched to idle is to enable a clock that uses it (tipb_ck, > > > dma_ck, or tc_ck or one of its children in this case, right?). > > > > > > I assume there is no bug in omapfb nor lcdc, as that would be already > > > detected. Maybe it would be better to fix > > > drivers/video/omap/lcd_ams_delta.c (or > > > arch/arm/mach-omap1/board-ams-delta), but I don't know what clock > > > should I enable, if any. > > > > More looking at it, I found that might be omap_dma_running() from > > arch/arm/plat-omap/dma.c that needs correction. It already checks for LCD > > dma running for OMAP1610, but does nothing similiar for 1510. I have > > revisited http://focus.ti.com/lit/ug/spru674/spru674.pdf, but found no > > hint how to do that in a 1610 similiar way. > > Hmm to me it looks like the OMAP_DMA_CCR_EN should be set in one of the > channels if enabled. Maybe you need add a similar check somewhere in > the *_lcd_dma_* functions too in dma.c? Tony, It sounds reasonable, but the problem is that in the OMAP5910 documentation I can find no DMA_CCR equivalent in the LCD dedicated DMA channel register set, nor EN equivalent in the DMA_LCD_CTRL register. I have had a look at *_lcd_dma_*, as you suggested, and found this: /* * Set the Enable bit only if an external controller is * connected. Otherwise the OMAP internal controller will * start the transfer when it gets enabled. */ if (enable_1510_mode || !lcd_dma.ext_ctrl) return; That may suggest checking for LCD controller, not DMA channel, enable bit could give an answer if LCD DMA is likely to be running or not. So maybe adding a function to drivers/video/omap/lcdc.c that would check for OMAP_LCDC_CONTROL:OMAP_LCDC_CTRL_LCD_EN, then invoke that function from omap_dma_running() in case of omap1510 could be a proper solution. However, that would affect not only Amstrad Delta, but all 1510 based machines. Since there were no reports about broken LCD DMA on 1510, I'd rather get a confirmation from omap guys, more experienced than me, that the solution proposed is correct and should work not only for my Amstrad Delta before I get that way. Thanks, Janusz -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
