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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjI2MDA5MiBTYWx0ZWRfX25vI7AFFmnOf Oe9to57w4BGRdGiU1qSn6Qz/bUBoeyC63338FvI5chvjM3jYNnt+SdRp+82/vGtxJtqsgzi94Qc TyYGJL/lfcpaPNgWG1+IVM+MKRpj/Kk84gB1HE5FrnShQNkZYNLK6kSl+eIAZKW0N8PivLdcmKM jQV1tDx4rFZqkY/hptCnvde/a8C7R8hGEXcZ1jgs0nACp9EbplGTK+lPje9+oGeHP/MtU2/bczX 9H9AiVeWSYysxflw6sLCJWxLMdT6UraXXxo8p3yTlioYnRWyI2+DfZjghawi2BwGr0W7F02VAr6 r2LzO1uf9QVVyEN2Q1w6ibvPCL3Csleu++4JDvO9fxmagNY7IUghMikcv49yhrvWOk84G5hnGuV VqlFQFrzzcV9+uijM+Rfz+I+rsIs8paWBrLBBv/JK9RofFcXUgw7fXJqhFmE6OLKTAKbR5hjQRx pH1Gbk868PCj8nn/QJw== X-Authority-Analysis: v=2.4 cv=KNlqylFo c=1 sm=1 tr=0 ts=6a3e61bc cx=c_pps a=Uww141gWH0fZj/3QKPojxA==:117 a=j4ogTh8yFefVWWEFDRgCtg==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=j3I-O8hsx3pVybSV4xQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=PxkB5W3o20Ba91AHUih5:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNjI2MDA5MiBTYWx0ZWRfX2JiSqxQNzlIM /DZHCjh397Gbyn2LrlQ4vJNgNMom8yrwFCdyPll02qp9HjsS/LzQIwd6617NKICCeKC8BeS2Dko 0Tkojt5bfyh0aTkmm/Wml6uicRHMwOU= X-Proofpoint-ORIG-GUID: 0ZYktjSimpdBi4fWu33ZgcdrT92qSBbh X-Proofpoint-GUID: 0ZYktjSimpdBi4fWu33ZgcdrT92qSBbh X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-26_03,2026-06-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 bulkscore=0 malwarescore=0 spamscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606260092 On 6/25/2026 2:17 PM, Konrad Dybcio wrote: > On 6/19/26 12:54 PM, Bibek Kumar Patro wrote: >> >> >> On 6/18/2026 2:58 PM, Konrad Dybcio wrote: >>> On 6/17/26 4:26 PM, Bibek Kumar Patro wrote: >>>> >>>> >>>> On 6/16/2026 5:51 AM, Dmitry Baryshkov wrote: >>>>> On Mon, Jun 15, 2026 at 06:36:51PM +0530, Bibek Kumar Patro wrote: >>>>>> >>>>>> >>>>>> On 6/8/2026 7:25 PM, Dmitry Baryshkov wrote: >>>>>>> On Tue, May 26, 2026 at 08:12:03PM +0530, Bibek Kumar Patro wrote: >>>>>>>> On some SoCs the SMMU registers require an active interconnect >>>>>>>> bandwidth vote to be accessible. While other clients typically >>>>>>>> satisfy this requirement implicitly, certain corner cases (e.g. >>>>>>>> during sleep/wakeup transitions) can leave the SMMU without a >>>>>>>> vote, causing intermittent register access failures. >>>>>>>> >>>>>>>> Add support for an optional interconnect path to the arm-smmu >>>>>>>> driver and vote for bandwidth while the SMMU is active. The path >>>>>>>> is acquired from DT if present and ignored otherwise. >>>>>>>> >>>>>>>> The bandwidth vote is enabled before accessing SMMU registers >>>>>>>> during probe and runtime resume, and released during runtime >>>>>>>> suspend and on error paths. >>>>>>>> >>>>>>>> Generally, from an architectural perspective, GEM_NOC and DDR are >>>>>>>> expected to have an active vote whenever the adreno_smmu block is >>>>>>>> powered on. In most common use cases, this requirement is implicitly >>>>>>>> satisfied because other GPU-related clients (for example, the GMU >>>>>>>> device) already hold a GEM_NOC vote when adreno_smmu is enabled. >>>>>>>> >>>>>>>> However, there are certain corner cases, such as during sleep/wakeup >>>>>>>> transitions, where the GEM_NOC vote can be removed before adreno_smmu >>>>>>>> is powered down. If adreno_smmu is then accessed while the interconnect >>>>>>>> vote is missing, it can lead to the observed failures. Because of the >>>>>>>> precise ordering involved, this scenario is difficult to reproduce >>>>>>>> consistently. >>>>>>>> (also GDSC is involved in adreno usecases can have an independent vote) >>>>>>>> >>>>>>>> Signed-off-by: Bibek Kumar Patro >>>>>>>> --- >>>>>>>>     drivers/iommu/arm/arm-smmu/arm-smmu.c | 57 +++++++++++++++++++++++++++++++++-- >>>>>>>>     drivers/iommu/arm/arm-smmu/arm-smmu.h |  2 ++ >>>>>>>>     2 files changed, 57 insertions(+), 2 deletions(-) >>>>>>>> >>>>>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c >>>>>>>> index 0bd21d206eb3e75c3b9fb1364cdc92e82c5aa499..07c7e44ec6a5bd1488f00f87d859a20495e46601 100644 >>>>>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c >>>>>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c >>>>>>>> @@ -53,6 +53,11 @@ >>>>>>>>     #define MSI_IOVA_BASE            0x8000000 >>>>>>>>     #define MSI_IOVA_LENGTH            0x100000 >>>>>>>> +/* Interconnect bandwidth vote values for the SMMU register access path */ >>>>>>>> +#define ARM_SMMU_ICC_AVG_BW        0 >>>>>>>> +#define ARM_SMMU_ICC_PEAK_BW_HIGH    1000 >>>>>>> >>>>>>> totally random numbers, which might be different for non-Qualcomm platform. >>>>>>> >>>>>> >>>>>> Ideally, any non-zero value would be enough to keep the path active. >>>>> >>>>> This is true for Qualcomm devices. However, you are adding this to a >>>>> generic code. >>>>> >>>>>> Here 1 Would be enough to keep the path active, but might be too small to >>>>>> reliably keep the bus active. >>>>>> Other is UINT_MAX, which will reliably keep the bus active but might cause a >>>>>> power penalty. >>>>>> >>>>>> #define ARM_SMMU_ICC_PEAK_BW_HIGH    UINT_MAX >>>>>> >>>>>> seems to be suitable here to reliably keep the bus active by BCM >>>>>> for both Qualcomm and non-Qualcomm platforms (with some power penalty). >>>>>> >>>>>> LMK, if you feel otherwise. >>>>> >>>>> Shift it to the qcom instance or provide platform-specific values? (My >>>>> preference would be towards the first solution). >>>>> >>>> >>>> >>>> To support platform-specific values, we may need to introduce a LUT-based approach in the driver. (Bandwidth voting values cannot be placed in device-tree property IIRC ?) >>>> >>>> Currently, all Qualcomm platforms use 0x1000 for SMMU ICC voting. I >>> >>> (you used decimal 1000) >>> >> >> It's my bad, i meant 1000 only >> (I'll check on the icc_bw calculation to get clarity on the values) >> >>>> can evaluate if this could be moved to a Qualcomm-specific >>>> implementation. >>> >>> Add a vendor hook to arm_smmu_runtime_suspend/resume and handle it within >>> the QC driver >>> >> >> Just curious, wouldn't this apply for all the arm-smmu users in addition to Qualcomm devices as i mentioned here [1]. >> Vendor hook would make it Qualcomm specific. > > You're proposing to use a Qualcomm-specific bandwidth value so that > fits > Got it, It seems valid. Will be sharing the new implementation post testing in next revision. Thanks & regards, Bibek > Konrad > >> >> [1]: https://lore.kernel.org/all/984ff9c7-3eef-463c-a330-bf7acd063667@oss.qualcomm.com/ >> >> Thanks & regards, >> Bibek >> >>> Konrad >>