kernel/drivers/video/fbdev/omap2/dss/dispc.c, branch linux-4.3.y

Merge omapdss scaling fixes

2015-06-22T11:56:01Z

OMAPDSS: DISPC: scaler debug print

2015-06-17T12:44:29Z

Improve the DISPC debug print for scaling. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: do only y decimation on OMAP3

2015-06-17T12:44:29Z

The current driver does both x and y decimation on OMAP3 DSS. Testing shows that x decimation rarely works, leading to underflows. The exact reason for this is unclear, as the underflows seem to happen even with low pixel clock rates, and I would presume that if the DSS can manage a display with 140MHz pixel clock, it could manage x decimation with factor 2 with a low pixel clock (~30MHz). So it is possible that there is a problem somewhere else, in memory management, or DSS DMA, or similar. I have not found anything that would help this. So, to fix the downscaling scaling, this patch removes x decimation for OMAP3. This will limit some of the more demanding downscaling scenarios, but one could argue that using DSS to downscale such a large amount is insane in the first place, as the produced image is rather bad quality. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: check if scaling setup failed

2015-06-17T12:44:28Z

The DISPC's scaling code seems to presume that decimation always succeeds, and so we always do find a suitable downscaling setup. However, this is not the case, and the algorithm can fail. When that happens, the code just proceeds with wrong results, causing issues later. Add the necessary checks to bail out if the scaling algorithm failed. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: fix 64 bit issue in 5-tap

2015-06-17T12:44:28Z

The DISPC driver uses 64 bit arithmetic to calculate the required clock rate for scaling. The code does not seem to work correctly, and instead calculates with 32 bit numbers, giving wrong result. Fix the code by typecasting values to u64 first, so that the calculations do happen in 64 bits. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: fix row_inc for OMAP3

2015-06-17T12:44:28Z

pixel_inc and row_inc work differently on OMAP2/3 and OMAP4+ DSS. On OMAP2/3 DSS, the pixel_inc is _not_ added by the HW at the end of the line, after the last pixel, whereas on OMAP4+ it is. The driver currently works for OMAP4+, but does not handle OMAP2/3 correctly, which leads to tilted image when row_inc is used. This patch adds a flag to DISPC driver so that the pixel_inc is added when required. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: add check for scaling limits

2015-06-17T12:38:44Z

On OMAP3/AM43xx some scaling factors cause underflows/synclosts. After studying this, I found that sometimes the driver uses three-tap scaling with downscaling factor smaller than x0.5. This causes issues, as x0.5 is the limit for three-tap scaling. The driver has FEAT_PARAM_DOWNSCALE parameter, but that seems to be for five-tap scaling, which allows scaling down to x0.25. This patch adds checks for both horizontal and vertical scaling. For horizontal the HW always uses 5 taps, so the limit is x0.25. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: fix check_horiz_timing_omap3 args

2015-06-17T12:38:43Z

After calculating the required decimation for scaling, the dispc driver checks once more if the resulting configuration is valid by calling check_horiz_timing_omap3(). Earlier calls to this function have correctly used in_width and in_height as parameters, but the last call uses width and height. This causes the driver to possibly reject scaling that would work. This patch fixes the parameters. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: fix predecimation for YUV modes

2015-06-17T12:38:43Z

DISPC needs even input buffer width for YUV modes. The DISPC driver doesn't check this at the moment (although omapdrm does), but worse, when DISPC driver does x predecimation the result may be uneven. This causes sometimes sync losts, underflows, or just visual errors. This patch makes DISPC driver return an error if the user gives uneven input width for a YUV buffer. It also makes the input width even in case of predecimation. Signed-off-by: Tomi Valkeinen

OMAPDSS: DISPC: work-around for errata i631

2015-06-17T12:38:43Z

Errata i631 description: "When in YUV4:2:0 format in 1D burst, the DISPC DMA skips lines when fetching Chroma sampling." Workaround: "If YUV4:2:0-1D burst is required: Set DISPC_VIDp_ATTRIBUTES[22]DOUBLESTRIDE to 0x0 and DISPC_VIDp_ATTRIBUTES[13:12]ROTATION to 0x1 or 0x3" The description is somewhat confusing, but testing has shown that DSS fetches extra rows from memory when using NV12 format in 1D mode. If the memory after the framebuffer is inaccessible, this leads to OCP errors. The driver always uses DOUBLESTRIDE=0 when using 1D mode, so we only need to handle the ROTATION part. The issue exist on all OMAP4 and OMAP5 based DSS IPs. Signed-off-by: Tomi Valkeinen