Messages in this thread | | | Date | Wed, 22 Jun 2022 08:22:55 -0700 | Subject | Re: [PATCH 2/3] drm/msm/dp: Remove pixel_rate from struct dp_ctrl | From | Kuogee Hsieh <> |
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On 6/22/2022 12:24 AM, Dmitry Baryshkov wrote: > On 22/06/2022 05:59, Stephen Boyd wrote: >> Quoting Dmitry Baryshkov (2022-06-17 16:07:58) >>> On 17/06/2022 23:47, Stephen Boyd wrote: >>>> This struct member is stored to in the function that calls the >>>> function >>>> which uses it. That's possible with a function argument instead of >>>> storing to a struct member. Pass the pixel_rate as an argument instead >>>> to simplify the code. Note that dp_ctrl_link_maintenance() was storing >>>> the pixel_rate but never using it so we just remove the assignment >>>> from >>>> there. >>>> >>>> Cc: Kuogee Hsieh <quic_khsieh@quicinc.com> >>>> Signed-off-by: Stephen Boyd <swboyd@chromium.org> >>>> --- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.c | 57 >>>> ++++++++++++++++---------------- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.h | 1 - >>>> 2 files changed, 28 insertions(+), 30 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> index bd445e683cfc..e114521af2e9 100644 >>>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> @@ -1336,7 +1336,7 @@ static void dp_ctrl_set_clock_rate(struct >>>> dp_ctrl_private *ctrl, >>>> name, rate); >>>> } >>>> >>>> -static int dp_ctrl_enable_mainlink_clocks(struct dp_ctrl_private >>>> *ctrl) >>>> +static int dp_ctrl_enable_mainlink_clocks(struct dp_ctrl_private >>>> *ctrl, unsigned long pixel_rate) >>> >>> >>> I think we can read pixel_rate here rather than getting it as an >>> argument. We'd need to move handling (DP_TEST_LINK_PHY_TEST_PATTERN && >>> !ctrl->panel->dp_mode.drm_mode.clock) case here from dp_ctrl_on_link(). >> >> This is also called from dp_ctrl_on_stream() and >> dp_ctrl_reinitialize_mainlink(). In the dp_ctrl_on_stream() case we may >> divide the pixel_rate by 2 with widebus. We could move the >> dp_ctrl_on_link() code here, but then we also need to move widebus, and >> then I'm not sure which pixel rate to use. >> >> It looks like the test code doesn't care about widebus? And similarly, >> we may run the pixel clk faster until we get a modeset and then divide >> it for widebus. > > Good question. I'll let Kuogee or somebody else from Qualcomm to > comment on test code vs widebus vs pixel rate, as I don't know these > details. > > I'm not sure if we should halve the pixel clock in > dp_ctrl_on_stream_phy_test_report() or not if the widebus is supported. > From the current code I'd assume that we have to do this. Let's raise > this question in the corresponding patch discussion. > yes, phy test does not care pixel clock rate. >> Is that why you're suggesting to check >> !ctrl->panel->dp_mode.drm_mode.clock? I hesitate because it isn't a >> direct conversion, instead it checks some other stashed struct member. >> >> I'll also note that dp_ctrl_enable_mainlink_clocks() doesn't really use >> this argument except to print the value in drm_dbg_dp(). Maybe we should >> simply remove it from here instead? > > Yes, do it please. > >> >>>> @@ -1588,12 +1586,12 @@ static int >>>> dp_ctrl_on_stream_phy_test_report(struct dp_ctrl *dp_ctrl) >>>> { >>>> int ret; >>>> struct dp_ctrl_private *ctrl; >>>> + unsigned long pixel_rate; >>>> >>>> ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl); >>>> >>>> - ctrl->dp_ctrl.pixel_rate = ctrl->panel->dp_mode.drm_mode.clock; >>>> - >>>> - ret = dp_ctrl_enable_stream_clocks(ctrl); >>>> + pixel_rate = ctrl->panel->dp_mode.drm_mode.clock; >>>> + ret = dp_ctrl_enable_stream_clocks(ctrl, pixel_rate); >>> >>> I think we can take another step forward here. Read the >>> ctrl->panel->dp_mode.drm_mode.clock from within the >>> dp_ctrl_enable_stream_clocks() function. This removes the need to pass >>> pixel_rate as an argument here. >> >> This is also affected by widebus and if the function is called from >> dp_ctrl_on_stream() or dp_ctrl_on_stream_phy_test_report(). Maybe it >> would be better to inline dp_ctrl_enable_stream_clocks() to the >> callsites? That would probably simplify things because the function is >> mostly a wrapper around a couple functions. > > Yes, this sounds good. Then we can drop the drm_dbg_dp from it (as it > nearly duplicates the data that was just printed. > >
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