On Wed, Jan 26, 2022 at 07:42:48AM -0800, Doug Anderson wrote: > Hi, > > On Wed, Jan 26, 2022 at 6:58 AM Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > > > > From: Douglas Anderson <dianders@xxxxxxxxxxxx> > > > > Jitter was improved by lowering the MPLL bandwidth to account for high > > frequency noise in the rk3288 PLL. In each case MPLL bandwidth was > > lowered only enough to get us a comfortable margin. We believe that > > lowering the bandwidth like this is safe given sufficient testing. > > > > Changes since v3: > > - new patch > > > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > > Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx> > > (am from https://patchwork.kernel.org/patch/9223301/) > > Probably remove the "am from" line? It's not standard in upstream and > that link doesn't seem to go anywhere anymore... > > > > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 16 ++-------------- > > 1 file changed, 2 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c > > index c44eb4d2e2d5..77f82a4fd027 100644 > > --- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c > > +++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c > > @@ -176,20 +176,8 @@ static const struct dw_hdmi_mpll_config rockchip_mpll_cfg[] = { > > static const struct dw_hdmi_curr_ctrl rockchip_cur_ctr[] = { > > /* pixelclk bpp8 bpp10 bpp12 */ > > { > > - 40000000, { 0x0018, 0x0018, 0x0018 }, > > - }, { > > - 65000000, { 0x0028, 0x0028, 0x0028 }, > > - }, { > > - 66000000, { 0x0038, 0x0038, 0x0038 }, > > - }, { > > - 74250000, { 0x0028, 0x0038, 0x0038 }, > > - }, { > > - 83500000, { 0x0028, 0x0038, 0x0038 }, > > - }, { > > - 146250000, { 0x0038, 0x0038, 0x0038 }, > > - }, { > > - 148500000, { 0x0000, 0x0038, 0x0038 }, > > - }, { > > + 600000000, { 0x0000, 0x0000, 0x0000 }, > > + }, { > > This is what we did for rk3288. I can't personally vouch for the > effects on other SoCs. Fair enough. Rockchip has this patch in their downstream Kernel, so I am confident it works on SoCs newer as the rk3288 as well. I don't know how much they care about the older SoCs, but it seems there is only the rk3228 that is older than the rk3288 that is supported by this driver. Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
