[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 04:57:37 UTC 2023
On 3/30/2023 7:47 PM, Dmitry Baryshkov wrote:
> On 31/03/2023 04:33, Abhinav Kumar wrote:
>>
>>
>> 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.
>
> Ack, this is what I was looking for!
>
> so intf = line / num_intf?
>
Yes by definition, "line" is one horizontal line of pixels for the panel.
So intf = h_active of panel / num_intf
But here "line" is one line of pixels pulled by the interface.
So for dual dsi cases its = h_active of panel / 2
> Maybe I should explain the reason for my question:
>
> msm_dsc_get_pclk_per_line() uses intf_width, calculates pclk_per_line
> (not per intf). msm_dsc_get_dce_bytes_per_line() does the same thing
>
> In this patch we take slice_per_intf, divide it with slice_per_pkt and
> get pkt_per_line (rather than pkt_per_intf).
>
> This is what prompted my question regarding intf vs line.
>
Valid question. The terminology gets a bit confusing because.
pclk_per_line can be only per interface.
Thats because each interface can pull the pixels at different pclks.
If it helps, I would say, this is pclk_per_line for each interface.
OR in other words pclks needed to pull one line of pixels for each
interface.
But if i changed it to slice_per_line that would be wrong because then
line becomes the full panel horizontal line.
>>
>>>>
>>>> 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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