Re: [PATCH RESEND v4 4/4] drm/bridge: nwl-dsi: Correct MIPI DSI horizontal sync timing

[Esben Haabendal <esben@geanix.com>]

Sorry for the premature send of the previous reply.


"Liu Ying" <victor.liu@nxp.com> writes:

>>
>> diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
>> index f3f4334136c0..eb604733eea0 100644
>> --- a/drivers/gpu/drm/bridge/nwl-dsi.c
>> +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
>> @@ -22,6 +22,7 @@
>>  #include <linux/reset.h>
>>  #include <linux/sys_soc.h>
>>  #include <linux/time64.h>
>> +#include <linux/math64.h>
>
> Sort the header files alphabetically.

Will do.

>> +	hfp = roundup(hfp, 2);
>> +	hbp = roundup(hbp, 2);
>> +	hsa = roundup(hsa, 2);
>> +
>> +	/*
>> +	 * We need to subtract the packet header length: 32
>> +	 * In order to make sure we don't get negative values,
>> +	 * subtract a proportional value to the total length of the
>> +	 * horizontal blanking duration.
>> +	 */
>> +	h_blank = hfp + hbp + hsa;
>> +
>> +	if (h_blank) {
>> +		pkt_len = min(hfp, roundup(((hfp * 100 / h_blank) * 32) / 100, 2));
>> +		pkt_hdr_len = pkt_len;
>> +		hfp -= pkt_len;
>> +
>> +		pkt_len = min(hbp, roundup(((hbp * 100 / h_blank) * 32) / 100, 2));
>> +		pkt_hdr_len += pkt_len;
>> +		hbp -= pkt_len;
>> +
>> +		pkt_len = min(hsa, 32 - pkt_hdr_len);
>> +		pkt_hdr_len += pkt_len;
>> +		hsa -= pkt_len;
>> +		if (pkt_hdr_len != 32)
>> +			dev_warn(dsi->dev,
>> +				 "Unable to subtract packet header length fully: %d left\n",
>> +				 32 - pkt_hdr_len);
>> +	}
>> +
>> +	DRM_DEV_DEBUG_DRIVER(dsi->dev, "Register values: hfp=%d hbp=%d hsa=%d\n", hfp, hbp, hsa);
>> +
>> +	nwl_dsi_write(dsi, NWL_DSI_HFP, hfp);
>> +	nwl_dsi_write(dsi, NWL_DSI_HBP, hbp);
>> +	nwl_dsi_write(dsi, NWL_DSI_HSA, hsa);
>>
>>  	nwl_dsi_write(dsi, NWL_DSI_ENABLE_MULT_PKTS, 0x0);
>>  	nwl_dsi_write(dsi, NWL_DSI_BLLP_MODE, 0x1);
>>
>> --
>> 2.56.0
>>
>
> Not sure if the fix is 100% correct, but it is a correct direction to
> change the blanking packet payload size from in pixel clocks to in bytes,
> so better than no fix:
> Acked-by: Liu Ying <victor.liu@nxp.com>

Thanks. With the information available to me, this is the best I can do.

/Esben