Messages in this thread | | | Subject | Re: [PATCH v3] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer | From | Dafna Hirschfeld <> | Date | Mon, 20 Sep 2021 17:19:19 +0200 |
| |
On 01.09.21 10:50, Hans Verkuil wrote: > On 25/08/2021 12:17, Dafna Hirschfeld wrote: >> From: Alexandre Courbot <acourbot@chromium.org> >> >> When running memcpy_toio: >> memcpy_toio(send_obj->share_buf, buf, len); >> it was found that errors appear if len is not a multiple of 8: >> >> [58.350841] mtk-mdp 14001000.rdma: processing failed: -22 >> >> This patch ensures the copy of a multile of 8 size by calling > > multile -> multiple > >> round_up(len, 8) when copying >> >> Fixes: e6599adfad30 ("media: mtk-vpu: avoid unaligned access to DTCM buffer.") >> Signed-off-by: Alexandre Courbot <acourbot@chromium.org> >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> >> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> >> --- >> changes since v2: >> 1. do the extra copy only if len is not multiple of 8 >> >> changes since v1: >> 1. change sign-off-by tags >> 2. change values to memset >> >> drivers/media/platform/mtk-vpu/mtk_vpu.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c b/drivers/media/platform/mtk-vpu/mtk_vpu.c >> index ec290dde59cf..658161ee3e4e 100644 >> --- a/drivers/media/platform/mtk-vpu/mtk_vpu.c >> +++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c >> @@ -349,7 +349,16 @@ int vpu_ipi_send(struct platform_device *pdev, >> } >> } while (vpu_cfg_readl(vpu, HOST_TO_VPU)); >> >> - memcpy_toio(send_obj->share_buf, buf, len); >> + if (len % 8 != 0) { > > You need to add a comment here explaining why this is done (basically what > you also say in the commit log). > > Otherwise people would have to dig into the git log to figure out why this > code is the way it is. > > Is len often not a multiple of 8? If that's the case, then it might be easier > to just always do the memset/memcpy.
I wrote a program that prints the sizes of all possible messages: http://ix.io/3zsr compiling it to arm64 gives:
sizeof(mdp_ipi_comm) is 24 sizeof(mdp_ipi_init) is 16
sizeof(venc_ap_ipi_msg_deinit) is 8 sizeof(venc_ap_ipi_msg_enc_ext) is 164 sizeof(venc_ap_ipi_msg_enc) is 32 sizeof(venc_ap_ipi_msg_set_param_ext) is 144 sizeof(venc_ap_ipi_msg_set_param) is 48 sizeof(venc_ap_ipi_msg_init) is 16
sizeof(vdec_ap_ipi_cmd) is 8 sizeof(vdec_ap_ipi_init) is 16 sizeof(vdec_ap_ipi_dec_start) is 24
BUT, when printing the size in the kernel I got "sizeof(mdp_ipi_comm) = 20" and found out that this is due to the macro #pragma pack(push, 4) in mtk_mdp_ipi.h
so for mdp it makes sens to always do the memset/memcpy but for mtk-vcodec it is not necessary. In addition, if the message is one of 'venc_ap_ipi_msg_enc_ext' or 'venc_ap_ipi_msg_set_param_ext' then vpu_ipi_send will fail in the beginning of the function since in those cases we have 'len > sizeof(send_obj->share_buf)'. so I should send a patch that set SHARE_BUF_SIZE to e.g. 200
I also found out that adding #pragma pack(push, 4) to the definitions of the mtk-vcodec messages has no influence but maybe this should be added since we copy those messages to hw , so might avoid future bugs.
thanks, Dafna
> > Regards, > > Hans > >> + unsigned char data[SHARE_BUF_SIZE]; >> + >> + memset(data + len, 0, sizeof(data) - len); >> + memcpy(data, buf, len); >> + memcpy_toio(send_obj->share_buf, data, round_up(len, 8)); >> + } else { >> + memcpy_toio(send_obj->share_buf, buf, len); >> + } >> + >> writel(len, &send_obj->len); >> writel(id, &send_obj->id); >> >> >
| |