[Freedreno] [PATCH RFC 5/5] drm/msm/dsi: Use MSM and DRM DSC helper methods
Abhinav Kumar
quic_abhinavk at quicinc.com
Fri Mar 31 01:33:08 UTC 2023
On 3/30/2023 5:16 PM, Dmitry Baryshkov wrote:
> On Fri, 31 Mar 2023 at 03:07, Jessica Zhang <quic_jesszhan at quicinc.com> wrote:
>>
>>
>>
>> On 3/30/2023 4:14 PM, Dmitry Baryshkov wrote:
>>> On 31/03/2023 01:49, Jessica Zhang wrote:
>>>>
>>>>
>>>> On 3/29/2023 4:48 PM, Dmitry Baryshkov wrote:
>>>>> On 30/03/2023 02:18, Jessica Zhang wrote:
>>>>>> Use MSM and DRM DSC helper methods.
>>>>>>
>>>>>> Signed-off-by: Jessica Zhang <quic_jesszhan at quicinc.com>
>>>>>> ---
>>>>>> drivers/gpu/drm/msm/dsi/dsi_host.c | 18 ++++++++++++------
>>>>>> 1 file changed, 12 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>>>> b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>>>> index 74d38f90398a..7419fe58a941 100644
>>>>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>>>> @@ -31,6 +31,7 @@
>>>>>> #include "msm_kms.h"
>>>>>> #include "msm_gem.h"
>>>>>> #include "phy/dsi_phy.h"
>>>>>> +#include "disp/msm_dsc_helper.h"
>>>>>> #define DSI_RESET_TOGGLE_DELAY_MS 20
>>>>>> @@ -841,14 +842,14 @@ static void dsi_update_dsc_timing(struct
>>>>>> msm_dsi_host *msm_host, bool is_cmd_mod
>>>>>> {
>>>>>> struct drm_dsc_config *dsc = msm_host->dsc;
>>>>>> u32 reg, reg_ctrl, reg_ctrl2;
>>>>>> - u32 slice_per_intf, total_bytes_per_intf;
>>>>>> + u32 slice_per_intf;
>>>>>> u32 pkt_per_line;
>>>>>> u32 eol_byte_num;
>>>>>> /* first calculate dsc parameters and then program
>>>>>> * compress mode registers
>>>>>> */
>>>>>> - slice_per_intf = DIV_ROUND_UP(hdisplay, dsc->slice_width);
>>>>>> + slice_per_intf = msm_dsc_get_slice_per_intf(dsc, hdisplay);
>>>>>
>>>>> This looks good
>>>>>
>>>>>> /*
>>>>>> * If slice_count is greater than slice_per_intf
>>>>>> @@ -858,10 +859,10 @@ static void dsi_update_dsc_timing(struct
>>>>>> msm_dsi_host *msm_host, bool is_cmd_mod
>>>>>> 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 = msm_dsc_get_eol_byte_num(msm_host->dsc, hdisplay,
>>>>>> + dsi_get_bpp(msm_host->format));
>>>>>> - eol_byte_num = total_bytes_per_intf % 3;
>>>>>> - pkt_per_line = slice_per_intf / dsc->slice_count;
>>>>>> + pkt_per_line = slice_per_intf / MSM_DSC_SLICE_PER_PKT;
>>>>>
>>>>> And for these values the result is definitely changed. Separate patch
>>>>> & description please. Just in case, "values per downstream kernel" is
>>>>> not a proper description for such changes.
>>>>
>>>> Hi Dmitry,
>>>>
>>>> Sure, I can put this into a separate patch.
>>>>
>>>> The reason this was changed from slice_count to SLICE_PER_PKT was
>>>> because slice count and slice per packet aren't always equivalent.
>>>> There can be cases where panel configures DSC to have multiple soft
>>>> slices per interface, but the panel only specifies 1 slice per packet.
>>>
>>> Please put this nice description into the commit message. It is exactly
>>> what I was looking for!
>>>
>>> BTW: Do you expect to change MSM_DSC_SLICE_PER_PKT later or it will stay
>>> at "1"? If so, it might be easier to drop it and instead add a comment.
>>
>> MSM_DSC_SLICE_PER_PKT is the default value for panels that don't specify
>> a slice_per_pkt value. (Now that I think about it, might be better to
>> call it MSM_DSC_DEFAULT_SLICE_PER_PKT instead...)
>
> Note, there is no slice_per_pkt in drm_dsc_config, so we must come up
> with another way to pass this data from the panel or to deduce the
> value in our driver.
>
>>
>> I don't expect it to change in the future, but it's a little more
>> readable than just dividing by 1 IMO. If you prefer dropping the macro
>> and adding a comment, I'm also okay with that.
>
> There is no need to divide by 1, the value doesn't change. So I'd
> probably prefer something like:
>
> /* Default to 1 slice per packet */
> if (panel_slice_per_pkt)
> pkt_per_line = slice_per_intf / panel_slice_per_pkt;
> else
> pkt_per_line = slice_per_intf;
>
> Or:
>
> /* Default to 1 slice per packet */
> slice_per_pkt = 1;
> if (panel_slice_per_pkt)
> slice_per_pkt = panel_slice_per_pkt;
> pkt_per_line = slice_per_intf / slice_per_pkt;
>
> BTW: could you possibly change 'intf' to 'line' to v2? It seems there
> is a mixture of them through the code. If there is a difference
> between intf and line which is not yet posted, it's fine to keep the
> current code. WDYT?
>
No, I dont agree with the change from intf to line.
In case of dual DSI, intf is not equal to line.
2 intfs = 1 line
Hence that distinction is necessary.
>>
>> Thanks,
>>
>> Jessica Zhang
>>
>>>
>>> Regarding eol_byte_num, probably the best explanation would be that is
>>> is a size of a padding rather than a size of a trailer bytes in a line
>>> (and thus original calculation was incorrect).
>>>
>>>>
>>>>>
>>>>>> if (is_cmd_mode) /* packet data type */
>>>>>> reg =
>>>>>> DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(MIPI_DSI_DCS_LONG_WRITE);
>>>>>> @@ -911,6 +912,11 @@ static void dsi_timing_setup(struct
>>>>>> msm_dsi_host *msm_host, bool is_bonded_dsi)
>>>>>> DBG("");
>>>>>> + if (msm_host->mode_flags & MIPI_DSI_MODE_VIDEO)
>>>>>> + /* Default widebus_en to false for now. */
>>>>>> + hdisplay = msm_dsc_get_pclk_per_line(msm_host->dsc,
>>>>>> mode->hdisplay,
>>>>>> + dsi_get_bpp(msm_host->format));
>>>>>> +
>>>>>
>>>>> This is definitely something new and thus should probably go into a
>>>>> separate patch and be described. Also I'm not sure how does that
>>>>> interact with the hdisplay-related calculations below, under the
>>>>> if(dsc) clause.
>>>>
>>>> After double-checking the math here, I think this part of the change
>>>> is actually wrong. pclk_per_line is essentially doing hdisplay / 3,
>>>> which is a repeat of what's being done in the `if (dsc)` block.
>>>>
>>>> Will replace `hdisplay /= 3` with the pclk_per_line calculation.
>>>
>>> Thanks!
>>>
>>>>
>>>> Thanks,
>>>>
>>>> Jessica Zhang
>>>>
>>>>>
>>>>>> /*
>>>>>> * For bonded DSI mode, the current DRM mode has
>>>>>> * the complete width of the panel. Since, the complete
>>>>>> @@ -1759,7 +1765,7 @@ static int dsi_populate_dsc_params(struct
>>>>>> msm_dsi_host *msm_host, struct drm_dsc
>>>>>> return ret;
>>>>>> }
>>>>>> - dsc->initial_scale_value = 32;
>>>>>> + dsc->initial_scale_value =
>>>>>> drm_dsc_calculate_initial_scale_value(dsc);
>>>>>
>>>>> This is fine, we only support 8bpp where these values match.
>>>>>
>>>>>> dsc->line_buf_depth = dsc->bits_per_component + 1;
>>>>>> return drm_dsc_compute_rc_parameters(dsc);
>>>>>>
>>>>>
>>>>> --
>>>>> With best wishes
>>>>> Dmitry
>>>>>
>>>
>>> --
>>> With best wishes
>>> Dmitry
>>>
>
>
>
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