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Message-ID: <20230614153335.w7mej6mate5tki5w@ripper>
Date: Wed, 14 Jun 2023 08:33:35 -0700
From: Bjorn Andersson <andersson@...nel.org>
To: Sarannya S <quic_sarannya@...cinc.com>
Cc: quic_bjorande@...cinc.com, arnaud.pouliquen@...s.st.com,
swboyd@...omium.org, quic_clew@...cinc.com,
mathieu.poirier@...aro.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
Deepak Kumar Singh <quic_deesin@...cinc.com>,
Andy Gross <agross@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: Re: [PATCH V7 2/3] rpmsg: glink: Add support to handle signals
command
On Sat, Apr 22, 2023 at 04:12:06PM +0530, Sarannya S wrote:
> From: Chris Lew <quic_clew@...cinc.com>
>
> Remote peripherals send signal notifications over glink with commandID 15.
>
> Add support to send and receive the signal command and based signals
> enable or disable flow control with remote host.
>
> Signed-off-by: Chris Lew <quic_clew@...cinc.com>
> Signed-off-by: Deepak Kumar Singh <quic_deesin@...cinc.com>
> Signed-off-by: Sarannya S <quic_sarannya@...cinc.com>
> ---
> drivers/rpmsg/qcom_glink_native.c | 64 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 01d2805..ff5e926 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -16,6 +16,7 @@
> #include <linux/rpmsg.h>
> #include <linux/sizes.h>
> #include <linux/slab.h>
> +#include <linux/termios.h>
> #include <linux/workqueue.h>
> #include <linux/mailbox_client.h>
>
> @@ -197,9 +198,15 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops;
> #define GLINK_CMD_TX_DATA_CONT 12
> #define GLINK_CMD_READ_NOTIF 13
> #define GLINK_CMD_RX_DONE_W_REUSE 14
> +#define GLINK_CMD_SIGNALS 15
>
> #define GLINK_FEATURE_INTENTLESS BIT(1)
>
> +#define NATIVE_DTR_SIG NATIVE_DSR_SIG
> +#define NATIVE_DSR_SIG BIT(31)
> +#define NATIVE_RTS_SIG NATIVE_CTS_SIG
> +#define NATIVE_CTS_SIG BIT(30)
> +
> static void qcom_glink_rx_done_work(struct work_struct *work);
>
> static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
> @@ -1014,6 +1021,58 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
> return 0;
> }
>
> +/**
> + * qcom_glink_set_flow_control() - convert a signal cmd to wire format and
> + * transmit
> + * @ept: Rpmsg endpoint for channel.
> + * @enable: True/False - enable or disable flow control
> + * @dst: destination address of the endpoint
> + *
> + * Return: 0 on success or standard Linux error code.
> + */
> +static int qcom_glink_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + struct glink_channel *channel = to_glink_channel(ept);
> + struct qcom_glink *glink = channel->glink;
> + struct glink_msg msg;
> + u32 sigs = 0;
> +
> + if (enable)
> + sigs |= NATIVE_DTR_SIG | NATIVE_RTS_SIG;
> +
> + msg.cmd = cpu_to_le16(GLINK_CMD_SIGNALS);
> + msg.param1 = cpu_to_le16(channel->lcid);
> + msg.param2 = cpu_to_le32(sigs);
> +
> + return qcom_glink_tx(glink, &msg, sizeof(msg), NULL, 0, true);
> +}
> +
> +static int qcom_glink_handle_signals(struct qcom_glink *glink,
> + unsigned int rcid, unsigned int sigs)
> +{
> + struct glink_channel *channel;
> + unsigned long flags;
> + bool enable = false;
> +
> + spin_lock_irqsave(&glink->idr_lock, flags);
> + channel = idr_find(&glink->rcids, rcid);
> + spin_unlock_irqrestore(&glink->idr_lock, flags);
> + if (!channel) {
> + dev_err(glink->dev, "signal for non-existing channel\n");
> + return -EINVAL;
You don't handle this return value, so this works fine. But the other
cases of returning an error to qcom_glink_native_rx() indicates that no
further messages should be processed (e.g. because there's no sufficient
data in the FIFO).
But getting a signal on a non-existing channel is not something that's
going to be resolved until we get the next interrupt, so I think you
shouldn't propagate this error.
Which means that it would be better to make the return type void of this
function.
> + }
> +
> + if (!channel->ept.flow_cb)
> + return 0;
> +
> + if (sigs & (NATIVE_DSR_SIG | NATIVE_CTS_SIG))
> + enable = true;
I'd find it cleaner to skip the early initialization and have a single
point of assignment of enable, like:
enable = sigs & NATIVE_DSR_SIG || sigs & NATIVE_CTS_SIG;
And consolidate the flow_cb query/invocation to one place:
if (channel->eptf.flow_cb)
channel->ept.flow_cb(, enable);
Regards,
Bjorn
> +
> + channel->ept.flow_cb(channel->ept.rpdev, channel->ept.priv, enable);
> +
> + return 0;
> +}
> +
> void qcom_glink_native_rx(struct qcom_glink *glink)
> {
> struct glink_msg msg;
> @@ -1075,6 +1134,10 @@ void qcom_glink_native_rx(struct qcom_glink *glink)
> qcom_glink_handle_intent_req_ack(glink, param1, param2);
> qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
> break;
> + case GLINK_CMD_SIGNALS:
> + qcom_glink_handle_signals(glink, param1, param2);
> + qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
> + break;
> default:
> dev_err(glink->dev, "unhandled rx cmd: %d\n", cmd);
> ret = -EINVAL;
> @@ -1449,6 +1512,7 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
> .sendto = qcom_glink_sendto,
> .trysend = qcom_glink_trysend,
> .trysendto = qcom_glink_trysendto,
> + .set_flow_control = qcom_glink_set_flow_control,
> };
>
> static void qcom_glink_rpdev_release(struct device *dev)
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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