On 4/23/25 5:23 PM, Dmitry Baryshkov wrote:
> On 23/04/2025 17:55, Rob Clark wrote:
>> On Tue, Apr 22, 2025 at 4:57 PM Konrad Dybcio
>> <konrad.dyb...@oss.qualcomm.com> wrote:
>>>
>>> On 4/21/25 10:13 PM, Rob Clark wrote:
>>>> On Fri, Apr 18, 2025 at 9:00 AM Akhil P Oommen <quic_akhi...@quicinc.com>
>>>> wrote:
>>>>>
>>>>> On 4/18/2025 6:40 AM, Connor Abbott wrote:
>>>>>> On Thu, Apr 17, 2025, 1:50 PM Akhil P Oommen <quic_akhi...@quicinc.com>
>>>>>> wrote:
>>>>>>>
>>>>>>> On 4/17/2025 9:02 PM, Connor Abbott wrote:
>>>>>>>> On Thu, Apr 17, 2025 at 3:45 AM Akhil P Oommen
>>>>>>>> <quic_akhi...@quicinc.com> wrote:
>>>>>>>>>
>>>>>>>>> On 4/10/2025 11:13 PM, Konrad Dybcio wrote:
>>>>>>>>>> From: Konrad Dybcio <konrad.dyb...@oss.qualcomm.com>
>>>>>>>>>>
>>>>>>>>>> The Highest Bank address Bit value can change based on memory type
>>>>>>>>>> used.
>>>>>>>>>>
>>>>>>>>>> Attempt to retrieve it dynamically, and fall back to a reasonable
>>>>>>>>>> default (the one used prior to this change) on error.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Konrad Dybcio <konrad.dyb...@oss.qualcomm.com>
>>>>>>>>>> ---
>>>>>>>>>> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 15 ++++++++++++++-
>>>>>>>>>> 1 file changed, 14 insertions(+), 1 deletion(-)
>>>>>>>>>>
>>>>>>>>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>>>>>>>> b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>>>>>>>> index
>>>>>>>>>> 06465bc2d0b4b128cddfcfcaf1fe4252632b6777..a6232b382bd16319f20ae5f8f5e57f38ecc62d9f
>>>>>>>>>> 100644
>>>>>>>>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>>>>>>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>>>>>>>>>> @@ -13,6 +13,7 @@
>>>>>>>>>> #include <linux/firmware/qcom/qcom_scm.h>
>>>>>>>>>> #include <linux/pm_domain.h>
>>>>>>>>>> #include <linux/soc/qcom/llcc-qcom.h>
>>>>>>>>>> +#include <linux/soc/qcom/smem.h>
>>>>>>>>>>
>>>>>>>>>> #define GPU_PAS_ID 13
>>>>>>>>>>
>>>>>>>>>> @@ -587,6 +588,8 @@ static void a6xx_set_cp_protect(struct msm_gpu
>>>>>>>>>> *gpu)
>>>>>>>>>>
>>>>>>>>>> static void a6xx_calc_ubwc_config(struct adreno_gpu *gpu)
>>>>>>>>>> {
>>>>>>>>>> + int hbb;
>>>>>>>>>> +
>>>>>>>>>> gpu->ubwc_config.rgb565_predicator = 0;
>>>>>>>>>> gpu->ubwc_config.uavflagprd_inv = 0;
>>>>>>>>>> gpu->ubwc_config.min_acc_len = 0;
>>>>>>>>>> @@ -635,7 +638,6 @@ static void a6xx_calc_ubwc_config(struct
>>>>>>>>>> adreno_gpu *gpu)
>>>>>>>>>> adreno_is_a690(gpu) ||
>>>>>>>>>> adreno_is_a730(gpu) ||
>>>>>>>>>> adreno_is_a740_family(gpu)) {
>>>>>>>>>> - /* TODO: get ddr type from bootloader and use 2 for
>>>>>>>>>> LPDDR4 */
>>>>>>>>>> gpu->ubwc_config.highest_bank_bit = 16;
>>>>>>>>>> gpu->ubwc_config.amsbc = 1;
>>>>>>>>>> gpu->ubwc_config.rgb565_predicator = 1;
>>>>>>>>>> @@ -664,6 +666,13 @@ static void a6xx_calc_ubwc_config(struct
>>>>>>>>>> adreno_gpu *gpu)
>>>>>>>>>> gpu->ubwc_config.highest_bank_bit = 14;
>>>>>>>>>> gpu->ubwc_config.min_acc_len = 1;
>>>>>>>>>> }
>>>>>>>>>> +
>>>>>>>>>> + /* Attempt to retrieve the data from SMEM, keep the above
>>>>>>>>>> defaults in case of error */
>>>>>>>>>> + hbb = qcom_smem_dram_get_hbb();
>>>>>>>>>> + if (hbb < 0)
>>>>>>>>>> + return;
>>>>>>>>>> +
>>>>>>>>>> + gpu->ubwc_config.highest_bank_bit = hbb;
>>>>>>>>>
>>>>>>>>> I am worried about blindly relying on SMEM data directly for HBB for
>>>>>>>>> legacy chipsets. There is no guarantee it is accurate on every chipset
>>>>>>>>> and every version of firmware. Also, until recently, this value was
>>>>>>>>> hardcoded in Mesa which matched the value in KMD.
>>>>>>>>
>>>>>>>> To be clear about this, from the moment we introduced host image
>>>>>>>> copies in Mesa we added support for querying the HBB from the kernel,
>>>>>>>> explicitly so that we could do what this series does without Mesa ever
>>>>>>>> breaking. Mesa will never assume the HBB unless the kernel is too old
>>>>>>>> to support querying it. So don't let Mesa be the thing that stops us
>>>>>>>> here.
>>>>>>>
>>>>>>> Thanks for clarifying about Mesa. I still don't trust a data source that
>>>>>>> is unused in production.
>>>>>>
>>>>>> Fair enough, I'm not going to argue with that part. Just wanted to
>>>>>> clear up any confusion about Mesa.
>>>>>>
>>>>>> Although, IIRC kgsl did set different values for a650 depending on
>>>>>> memory type... do you know what source that used?
>>>>>
>>>>> KGSL relies on an undocumented devicetree node populated by bootloader
>>>>> to detect ddrtype and calculates the HBB value based on that.
>>>>
>>>> Would it be reasonable to use the smem value, but if we find the
>>>> undocumented dt property, WARN_ON() if it's value disagrees with smem?
>>>>
>>>> That would at least give some confidence, or justified un-confidence
>>>> about the smem values
>>>
>>> The aforementioned value is populated based on the data that this
>>> driver reads out, and only on the same range of platforms that this
>>> driver happens to cater to
>>
>> Did I understand that correctly to mean that the dt property is based
>> on the same smem value that you are using? In that case, there should
>> be no argument against using the smem value as the source of truth.
>
> It is, but is done by the bootloader that knows exact format of the data.
Right, so the only point of concern here is the handwavy matching-by-size
logic.
Konrad
