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List:       dri-devel
Subject:    Re: [PATCH v3 04/15] drm/msm/a6xx: Extend and explain UBWC config
From:       Akhil P Oommen <quic_akhilpo () quicinc ! com>
Date:       2023-02-28 20:56:59
Message-ID: 26953463-dae1-0f07-9e4e-0314ee8ea81a () quicinc ! com
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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@linaro.org>
> > > ---
> > > 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.
> 
> 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)
> > > 


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