Re: [PATCH v2 05/20] rpmsg: glink: Allow unaligned data access

Arun Kumar Neelakantam
2017-08-28T11:46:45Z

On 8/24/2017 12:51 PM, Sricharan R wrote:
> From: Bjorn Andersson <bjorn.andersson@linaro.org>
>
> Glink protocol requires that each message is aligned
> on a 8 byte offset. This is purely a restriction
> from glink, so in order to support clients which
> do not adher to this, allow data packets of any size,
> but align the head index accordingly, effectively
> removing the alignment restriction.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>

Regards,
Arun N
> ---
> drivers/rpmsg/qcom_glink_native.c | 6 ------
> drivers/rpmsg/qcom_glink_rpm.c | 22 +++++++++++++++++++++-
> 2 files changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index ffdf88e..a6394cd 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -227,9 +227,6 @@ static int qcom_glink_tx(struct qcom_glink *glink,
> if (tlen >= glink->tx_pipe->length)
> return -EINVAL;
>
> - if (WARN(tlen % 8, "Unaligned TX request"))
> - return -EINVAL;
> -
> ret = mutex_lock_interruptible(&glink->tx_lock);
> if (ret)
> return ret;
> @@ -695,9 +692,6 @@ static int __qcom_glink_send(struct glink_channel *channel,
> __le32 left_size;
> } __packed req;
>
> - if (WARN(len % 8, "RPM GLINK expects 8 byte aligned messages\n"))
> - return -EINVAL;
> -
> req.msg.cmd = cpu_to_le16(RPM_CMD_TX_DATA);
> req.msg.param1 = cpu_to_le16(channel->lcid);
> req.msg.param2 = cpu_to_le32(channel->rcid);
> diff --git a/drivers/rpmsg/qcom_glink_rpm.c b/drivers/rpmsg/qcom_glink_rpm.c
> index 33daa32..cc73af0 100644
> --- a/drivers/rpmsg/qcom_glink_rpm.c
> +++ b/drivers/rpmsg/qcom_glink_rpm.c
> @@ -156,11 +156,31 @@ static void glink_rpm_tx_write(struct qcom_glink_pipe *glink_pipe,
> const void *data, size_t dlen)
> {
> struct glink_rpm_pipe *pipe = to_rpm_pipe(glink_pipe);
> + size_t tlen = hlen + dlen;
> + size_t aligned_dlen;
> unsigned int head;
> + char padding[8] = {0};
> + size_t pad;
> +
> + /* Header length comes from glink native and is always 4 byte aligned */
> + if (WARN(hlen % 4, "Glink Header length must be 4 bytes aligned\n"))
> + return;
> +
> + /*
> + * Move the unaligned tail of the message to the padding chunk, to
> + * ensure word aligned accesses
> + */
> + aligned_dlen = ALIGN_DOWN(dlen, 4);
> + if (aligned_dlen != dlen)
> + memcpy(padding, data + aligned_dlen, dlen - aligned_dlen);
>
> head = readl(pipe->head);
> head = glink_rpm_tx_write_one(pipe, head, hdr, hlen);
> - head = glink_rpm_tx_write_one(pipe, head, data, dlen);
> + head = glink_rpm_tx_write_one(pipe, head, data, aligned_dlen);
> +
> + pad = ALIGN(tlen, 8) - ALIGN_DOWN(tlen, 4);
> + if (pad)
> + head = glink_rpm_tx_write_one(pipe, head, padding, pad);
> writel(head, pipe->head);
> }
>