Messages in this thread | | | Date | Wed, 22 Jun 2022 10:24:54 +0300 | Subject | Re: [PATCH 2/3] drm/msm/dp: Remove pixel_rate from struct dp_ctrl | From | Dmitry Baryshkov <> |
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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.
> 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.
-- With best wishes Dmitry
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