Re: [Freedreno] [PATCH v3 04/15] drm/msm/a6xx: Extend and explain UBWC config

[Akhil P Oommen]

On 3/1/2023 2:14 AM, Akhil P Oommen wrote:
> On 3/1/2023 2:10 AM, Konrad Dybcio wrote:
>> On 28.02.2023 21:23, Akhil P Oommen wrote:
>>> On 2/23/2023 5:36 PM, Konrad Dybcio wrote:
>>>> Rename lower_bit to hbb_lo and explain what it signifies.
>>>> Add explanations (wherever possible to other tunables).
>>>>
>>>> Sort the variable definition and assignment alphabetically.
>>> Sorting based on decreasing order of line length is more readable, isn't it?
>> I can do that.
>>
>>>> Port setting min_access_length, ubwc_mode and hbb_hi from downstream.
>>>> Set default values for all of the tunables to zero, as they should be.
>>>>
>>>> Values were validated against downstream and will be fixed up in
>>>> separate commits so as not to make this one even more messy.
>>>>
>>>> A618 remains untouched (left at hw defaults) in this patch.
>>>>
>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
>>>> ---
>>>>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 55 ++++++++++++++++++++++++++++-------
>>>>  1 file changed, 45 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>> index c5f5d0bb3fdc..bdae341e0a7c 100644
>>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>> @@ -786,39 +786,74 @@ static void a6xx_set_cp_protect(struct msm_gpu *gpu)
>>>>  static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
>>>>  {
>>>>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
>>>> -	u32 lower_bit = 2;
>>>> +	/* Unknown, introduced with A640/680 */
>>>>  	u32 amsbc = 0;
>>>> +	/*
>>>> +	 * The Highest Bank Bit value represents the bit of the highest DDR bank.
>>>> +	 * We then subtract 13 from it (13 is the minimum value allowed by hw) and
>>>> +	 * write the lowest two bits of the remaining value as hbb_lo and the
>>>> +	 * one above it as hbb_hi to the hardware. The default values (when HBB is
>>>> +	 * not specified) are 0, 0.
>>>> +	 */
>>>> +	u32 hbb_hi = 0;
>>>> +	u32 hbb_lo = 0;
>>>> +	/* Whether the minimum access length is 64 bits */
>>>> +	u32 min_acc_len = 0;
>>>> +	/* Unknown, introduced with A650 family, related to UBWC mode/ver 4 */
>>>>  	u32 rgb565_predicator = 0;
>>>> +	/* Unknown, introduced with A650 family */
>>>>  	u32 uavflagprd_inv = 0;
>>>> +	/* Entirely magic, per-GPU-gen value */
>>>> +	u32 ubwc_mode = 0;
>>>>  
>>>>  	/* a618 is using the hw default values */
>>>>  	if (adreno_is_a618(adreno_gpu))
>>>>  		return;
>>>>  
>>>> -	if (adreno_is_a640_family(adreno_gpu))
>>>> +	if (adreno_is_a619(adreno_gpu)) {
>>>> +		/* HBB = 14 */
>>>> +		hbb_lo = 1;
>>>> +	}
>>>> +
>>>> +	if (adreno_is_a630(adreno_gpu)) {
>>>> +		/* HBB = 15 */
>>>> +		hbb_lo = 2;
>>>> +	}
>>>> +
>>>> +	if (adreno_is_a640_family(adreno_gpu)) {
>>>>  		amsbc = 1;
>>>> +		/* HBB = 15 */
>>>> +		hbb_lo = 2;
>>>> +	}
>>>>  
>>>>  	if (adreno_is_a650(adreno_gpu) || adreno_is_a660(adreno_gpu)) {
>>>> -		/* TODO: get ddr type from bootloader and use 2 for LPDDR4 */
>>>> -		lower_bit = 3;
>>>>  		amsbc = 1;
>>>> +		/* TODO: get ddr type from bootloader and use 2 for LPDDR4 */
>>>> +		/* HBB = 16 */
>>>> +		hbb_lo = 3;
>>>>  		rgb565_predicator = 1;
>>>>  		uavflagprd_inv = 2;
>>>>  	}
>>>>  
>>>>  	if (adreno_is_7c3(adreno_gpu)) {
>>>> -		lower_bit = 1;
>>>>  		amsbc = 1;
>>>> +		/* HBB is unset in downstream DTS, defaulting to 0 */
>>> This is incorrect. For 7c3 hbb value is 14. So hbb_lo should be 1. FYI, hbb configurations were moved to the driver from DT in recent downstream kernels.
>> Right, seems to have happened with msm-5.10. Though a random kernel I
>> grabbed seems to suggest it's 15 and not 14?
>>
>> https://github.com/sonyxperiadev/kernel/blob/aosp/K.P.1.0.r1/drivers/gpu/msm/adreno-gpulist.h#L1710
> We override that with 14 in a6xx_init() for LP4 platforms dynamically. Since 7c3 is only supported on LP4, we can hardcode 14 here.
> In the downstream kernel, there is an api (of_fdt_get_ddrtype()) to detect ddrtype. If we can get something like that in upstream, we should implement a similar logic here.
>
> -Akhil.
Also, I haven't closely reviewed other targets configuration you updated, but it is a good idea to leave the existing configurations here as it in this refactor patch. Any update should be a separate patch.

-Akhil.
>> Konrad
>>> -Akhil.
>>>>  		rgb565_predicator = 1;
>>>>  		uavflagprd_inv = 2;
>>>>  	}
>>>>  
>>>>  	gpu_write(gpu, REG_A6XX_RB_NC_MODE_CNTL,
>>>> -		rgb565_predicator << 11 | amsbc << 4 | lower_bit << 1);
>>>> -	gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, lower_bit << 1);
>>>> -	gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL,
>>>> -		uavflagprd_inv << 4 | lower_bit << 1);
>>>> -	gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, lower_bit << 21);
>>>> +		  rgb565_predicator << 11 | hbb_hi << 10 | amsbc << 4 |
>>>> +		  min_acc_len << 3 | hbb_lo << 1 | ubwc_mode);
>>>> +
>>>> +	gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, hbb_hi << 4 |
>>>> +		  min_acc_len << 3 | hbb_lo << 1 | ubwc_mode);
>>>> +
>>>> +	gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL, hbb_hi << 10 |
>>>> +		  uavflagprd_inv << 4 | min_acc_len << 3 |
>>>> +		  hbb_lo << 1 | ubwc_mode);
>>>> +
>>>> +	gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, min_acc_len << 23 | hbb_lo << 21);
>>>>  }
>>>>  
>>>>  static int a6xx_cp_init(struct msm_gpu *gpu)
>>>>