On 14/12/2022 11:25, Sibi Sankar wrote: > > > On 12/14/22 01:11, Krzysztof Kozlowski wrote: >> On 13/12/2022 15:07, Sibi Sankar wrote: >>> Update the bindings to reflect the addition of the new modem metadata >>> carveout reference to the memory-region property. >>> >>> Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx> >>> --- >>> .../devicetree/bindings/remoteproc/qcom,sc7180-mss-pil.yaml | 3 ++- >>> .../devicetree/bindings/remoteproc/qcom,sc7280-mss-pil.yaml | 3 ++- >>> 2 files changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/Documentation/devicetree/bindings/remoteproc/qcom,sc7180-mss-pil.yaml b/Documentation/devicetree/bindings/remoteproc/qcom,sc7180-mss-pil.yaml >>> index e4a7da8020f4..b1402bef0ebe 100644 >>> --- a/Documentation/devicetree/bindings/remoteproc/qcom,sc7180-mss-pil.yaml >>> +++ b/Documentation/devicetree/bindings/remoteproc/qcom,sc7180-mss-pil.yaml >>> @@ -95,6 +95,7 @@ properties: >>> items: >>> - description: MBA reserved region >>> - description: modem reserved region >>> + - description: metadata reserved region >> >> Which makes the third item now required, also for all out of tree DTS >> and other users of the bindings. Please write a bit more in commit msg >> why this is necessary (e.g. was it broken before?). I assume the driver >> does not break the ABI? > > I'll pad the commit msg with some of the additional info from patch 4. > commit c44094eee32f "arm64: dma: Drop cache invalidation from > arch_dma_prep_coherent()" exposed a bug in the driver affecting SoCs > from msm8996 on wards. The application processor accessing the > dynamically allocated region after giving control to the modem results > in a XPU violation. The recommended fix was to use a no-map carveout > instead and memunmap before giving control to the modem. The future > kernels that are paired with an older dtbs would crash during modem Then it's an ABI break. > bootup since we would continue to use dma_alloc_attr. But all the other > combinations (old kernel/new dtb) will continue to work. Does it mean that old kernel with old DTB was working? If yes, then it's ABI break without clear benefits. Best regards, Krzysztof
