On Thu, Jan 20, 2022 at 10:20 PM Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote: > > Hi Chen-Yu, > > I'll take patches 2-8. Got it. > So should I mark patch 1/8 as 'Rejected' or 'Changes Requested' in patchwork? I'd say "Changes Requested", but it won't really progress unless someone from Rockchip fills in the blanks about the wmb() though. ChenYu > Regards, > > Hans > > On 1/19/22 11:08, Chen-Yu Tsai wrote: > > Hi, > > > > On Wed, Jan 19, 2022 at 5:02 AM Ezequiel Garcia > > <ezequiel@xxxxxxxxxxxxxxxxxxxx> wrote: > >> > >> Hi Chen-Yu, > >> > >> The series looks good, thanks for picking up this task. > >> > >> Just a one comment. > >> > >> On Fri, Jan 07, 2022 at 05:34:48PM +0800, Chen-Yu Tsai wrote: > >>> In the earlier submissions of the Hantro/Rockchip JPEG encoder driver, a > >>> wmb() was inserted before the final register write that starts the > >>> encoder. In v11, it was removed and the second-to-last register write > >>> was changed to a non-relaxed write, which has an implicit wmb() [1]. > >>> The rockchip_vpu2 (then rk3399_vpu) variant is even weirder as there > >>> is another writel_relaxed() following the non-relaxed one. > >>> > >>> Turns out only the last writel() needs to be non-relaxed. Device I/O > >>> mappings already guarantee strict ordering to the same endpoint, and > >>> the writel() triggering the hardware would force all writes to memory > >>> to be observed before the writel() to the hardware is observed. > >>> > >>> [1] https://lore.kernel.org/linux-media/CAAFQd5ArFG0hU6MgcyLd+_UOP3+T_U-aw2FXv6sE7fGqVCVGqw@xxxxxxxxxxxxxx/ > >>> > >>> Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> > >>> --- > >>> drivers/staging/media/hantro/hantro_h1_jpeg_enc.c | 3 +-- > >>> drivers/staging/media/hantro/rockchip_vpu2_hw_jpeg_enc.c | 3 +-- > >>> 2 files changed, 2 insertions(+), 4 deletions(-) > >>> > >>> diff --git a/drivers/staging/media/hantro/hantro_h1_jpeg_enc.c b/drivers/staging/media/hantro/hantro_h1_jpeg_enc.c > >>> index 1450013d3685..03db1c3444f8 100644 > >>> --- a/drivers/staging/media/hantro/hantro_h1_jpeg_enc.c > >>> +++ b/drivers/staging/media/hantro/hantro_h1_jpeg_enc.c > >>> @@ -123,8 +123,7 @@ int hantro_h1_jpeg_enc_run(struct hantro_ctx *ctx) > >>> | H1_REG_AXI_CTRL_INPUT_SWAP32 > >>> | H1_REG_AXI_CTRL_OUTPUT_SWAP8 > >>> | H1_REG_AXI_CTRL_INPUT_SWAP8; > >>> - /* Make sure that all registers are written at this point. */ > >>> - vepu_write(vpu, reg, H1_REG_AXI_CTRL); > >>> + vepu_write_relaxed(vpu, reg, H1_REG_AXI_CTRL); > >>> > >> > >> As far as I can remember, this logic comes from really old Chromium Kernels. > >> You might be right, and this barrier isn't needed... but then OTOH the comment > >> is here for a reason, so maybe it is needed (or was needed on some RK3288 SoC revision). > > > > I just realized that my commit log is wrong. > > > > " ... a wmb() was inserted before the final register write that starts the > > encoder. ... " . It is actually before the second-to-last register write. > > > >> I don't have RK3288 boards near me, but in any case, I'm not sure > >> we'd be able to test this easily (maybe there are issues that only > >> trigger under a certain load). > > > > I see. I do have a Veyron around that I haven't used in awhile. But as you > > said, it might not be an obvious hardware limitation. > > > >> I'd personally avoid this one change, but if you are confident enough with it > >> that's fine too. > > > > Unfortunately they didn't leave a whole lot of clues around. For most hardware, > > as I mentioned in the commit log, I think the final non-relaxed write should > > suffice. I'd point to the decoder drivers not having any barriers or > > non-relaxed writes except the final one, but IIUC they are actually two > > distinct pieces of hardware. > > > > I suspect we will never know. This JPEG encoder doesn't seem to get used > > a lot. The VP8 and H.264 encoders on ChromeOS work correctly without the > > extra barrier and get tested a lot, but that's only testing the RK3399. > > > > Hans, would it be possible for you to skip this patch and pick the rest? > > Or would you like me to resent without this one? > > > > > > Thanks > > ChenYu > > > >> Thanks! > >> Ezequiel > >> > >>> reg = H1_REG_ENC_CTRL_WIDTH(MB_WIDTH(ctx->src_fmt.width)) > >>> | H1_REG_ENC_CTRL_HEIGHT(MB_HEIGHT(ctx->src_fmt.height)) > >>> diff --git a/drivers/staging/media/hantro/rockchip_vpu2_hw_jpeg_enc.c b/drivers/staging/media/hantro/rockchip_vpu2_hw_jpeg_enc.c > >>> index 4df16f59fb97..b931fc5fa1a9 100644 > >>> --- a/drivers/staging/media/hantro/rockchip_vpu2_hw_jpeg_enc.c > >>> +++ b/drivers/staging/media/hantro/rockchip_vpu2_hw_jpeg_enc.c > >>> @@ -152,8 +152,7 @@ int rockchip_vpu2_jpeg_enc_run(struct hantro_ctx *ctx) > >>> | VEPU_REG_INPUT_SWAP8 > >>> | VEPU_REG_INPUT_SWAP16 > >>> | VEPU_REG_INPUT_SWAP32; > >>> - /* Make sure that all registers are written at this point. */ > >>> - vepu_write(vpu, reg, VEPU_REG_DATA_ENDIAN); > >>> + vepu_write_relaxed(vpu, reg, VEPU_REG_DATA_ENDIAN); > >>> > >>> reg = VEPU_REG_AXI_CTRL_BURST_LEN(16); > >>> vepu_write_relaxed(vpu, reg, VEPU_REG_AXI_CTRL); > >>> -- > >>> 2.34.1.575.g55b058a8bb-goog > >>>
