Hi, Philipp,

Thanks for your comment.

On Wed, 2016-07-20 at 11:41 +0200, Philipp Zabel wrote:

Am Mittwoch, den 20.07.2016, 12:03 +0800 schrieb Bibby Hsieh:

quoted

From: Junzhi Zhao <redacted>

Pixel clock should be 297MHz when resolution is 4K.

Signed-off-by: Junzhi Zhao <redacted>
Signed-off-by: Bibby Hsieh <redacted>
---
 drivers/gpu/drm/mediatek/mtk_dpi.c |  184 +++++++++++++++++++++++++-----------
 1 file changed, 131 insertions(+), 53 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
index d05ca79..c0f04d2 100644
--- a/drivers/gpu/drm/mediatek/mtk_dpi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dpi.c

@@ -60,14 +60,35 @@ enum mtk_dpi_out_color_format {
 	MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL
 };
 
+enum mtk_dpi_clk_id {
+	MTK_DPI_CLK_DPI_ENGINE,
+	MTK_DPI_CLK_DPI_PIXEL,
+	MTK_DPI_CLK_TVD_PLL,
+	MTK_DPI_CLK_TVDPLL_MUX,
+	MTK_DPI_CLK_TVDPLL_D2,
+	MTK_DPI_CLK_TVDPLL_D4,
+	MTK_DPI_CLK_TVDPLL_D8,
+	MTK_DPI_CLK_TVDPLL_D16,
+	MTK_DPI_CLK_COUNT,
+};

I think this is going in the wrong direction. If the pixel clock output
isn't correct after a clk_set_rate(dpi->pixel_clk, rate), the clock
drivers should be fixed, not worked around in the dpi driver.

The TVDPLL_* mux and dividers are not direct inputs to the DPI module:

   tvdpll ("pll")
     |               ..|\
     v               ..| | mm_sel ----> mm_dpi_engine ("engine")
   tvdpll_594m(1/3)  ..|/
     |
     |`-> tvdpll_d2 -->|\
     |`-> tvdpll_d4 -->| | dpi0_sel --> mm_dpi_pixel ("pixel")
     |`-> tvdpll_d8 -->| |
     `--> tvdpll_d16 ->|/

Currently the code first sets the "pll" to the desired multiple of the
pixel clock manually (*3*4, *3*8) and than calls clk_set_rate on the
"pixel" clock which gets propagated by the clock framework up to
dpi0_sel. Since dpi0_sel doesn't have the CLK_SET_RATE_PARENT flag set,
it should just choose the tvdpll_d* input divider. I'd like not to give
the dpi driver direct access to all the intermediate clocks.

Ok, I will make some modifications according to your comment.

regards
Philipp