Messages in this thread | | | Date | Mon, 22 May 2023 14:27:01 -0700 | Subject | Re: [PATCH v4 5/5] drm/msm/dsi: Remove incorrect references to slice_count | From | Jessica Zhang <> |
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On 5/22/2023 2:01 PM, Marijn Suijten wrote: > On 2023-05-22 13:30:24, Jessica Zhang wrote: >> Currently, slice_count is being used to calculate word count and >> pkt_per_line. Instead, these values should be calculated using slice per >> packet, which is not the same as slice_count. >> >> Slice count represents the number of soft slices per interface, and its >> value will not always match that of slice per packet. For example, it is >> possible to have cases where there are multiple soft slices per interface >> but the panel specifies only one slice per packet. > > As discussed in many patches before, there is no definition of "soft > slices" anyhwere. Unless we can have that, and reference it, this > should more clearly explain what it means or leave out the word "soft" > altogether.
Hi Marijn,
Acked.
> >> Thus, use the default value of one slice per packet and remove slice_count >> from the aforementioned calculations. >> >> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration") >> Fixes: bc6b6ff8135c ("drm/msm/dsi: Use DSC slice(s) packet size to compute word count") >> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com> >> --- >> drivers/gpu/drm/msm/dsi/dsi_host.c | 26 ++++++++++++++++---------- >> 1 file changed, 16 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c >> index d04f8bbd707d..2eed99afdba9 100644 >> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c >> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c >> @@ -866,18 +866,17 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod >> */ >> slice_per_intf = msm_dsc_get_slices_per_intf(dsc, hdisplay); >> >> - /* >> - * If slice_count is greater than slice_per_intf >> - * then default to 1. This can happen during partial >> - * update. >> - */ >> - if (dsc->slice_count > slice_per_intf) >> - dsc->slice_count = 1; >> - >> total_bytes_per_intf = dsc->slice_chunk_size * slice_per_intf; >> >> eol_byte_num = total_bytes_per_intf % 3; >> - pkt_per_line = slice_per_intf / dsc->slice_count; >> + >> + /* >> + * Typically, pkt_per_line = slice_per_intf * slice_per_pkt. >> + * >> + * Since the current driver only supports slice_per_pkt = 1, >> + * pkt_per_line will be equal to slice per intf for now. >> + */ >> + pkt_per_line = slice_per_intf; >> >> if (is_cmd_mode) /* packet data type */ >> reg = DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(MIPI_DSI_DCS_LONG_WRITE); >> @@ -1001,7 +1000,14 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi) >> if (!msm_host->dsc) >> wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1; >> else >> - wc = msm_host->dsc->slice_chunk_size * msm_host->dsc->slice_count + 1; >> + /* >> + * When DSC is enabled, WC = slice_chunk_size * slice_per_packet + 1. >> + * Currently, the driver only supports default value of slice_per_packet = 1 >> + * >> + * TODO: Expand mipi_dsi_device struct to hold slice_per_packet info >> + * and adjust DSC math to account for slice_per_packet. >> + */ > > Either rename this all to slice_per_pkt, or rename the above comment to > slice_per_packet.
Acked.
Thanks,
Jessica Zhang
> > After improving on that: > > Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org> > > We all learned the wrong thing initially, thanks for clearing up that > slice_count != slice_per_pkt. > > - Marijn > >> + wc = msm_host->dsc->slice_chunk_size + 1; >> >> dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL, >> DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) | >> >> -- >> 2.40.1 >>
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