From mboxrd@z Thu Jan 1 00:00:00 1970 From: p.zabel@pengutronix.de (Philipp Zabel) Date: Thu, 11 Aug 2016 09:15:12 +0200 Subject: [PATCH v3 3/3] drm/mediatek: fix the wrong pixel clock when resolution is 4K In-Reply-To: <1470278311-22528-4-git-send-email-bibby.hsieh@mediatek.com> References: <1470278311-22528-1-git-send-email-bibby.hsieh@mediatek.com> <1470278311-22528-4-git-send-email-bibby.hsieh@mediatek.com> Message-ID: <1470899712.2493.16.camel@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am Donnerstag, den 04.08.2016, 10:38 +0800 schrieb Bibby Hsieh: > From: Junzhi Zhao > > Pixel clock should be 297MHz when resolution is 4K. > > Signed-off-by: Junzhi Zhao > Signed-off-by: Bibby Hsieh > --- > drivers/gpu/drm/mediatek/mtk_dpi.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c > index d05ca79..a90af59 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c > @@ -438,10 +438,14 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi, > } > > pix_rate = 1000UL * mode->clock; > - if (mode->clock <= 74000) > + if (mode->clock <= 27000) > + factor = 16 * 3; > + else if (mode->clock <= 74250) > factor = 8 * 3; > - else > + else if (mode->clock <= 167000) > factor = 4 * 3; > + else > + factor = 2 * 3; > pll_rate = pix_rate * factor; > > dev_dbg(dpi->dev, "Want PLL %lu Hz, pixel clock %lu Hz\n", Could you add a comment why this also changes the 74 MHz limit to 74.25 MHz and that adds a factor 16*3 for clocks <= 27 MHz ? regards Philipp