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Date:   Tue, 22 Aug 2017 14:42:17 +0530
From:   Arun Kumar Neelakantam <aneela@...eaurora.org>
To:     Sricharan R <sricharan@...eaurora.org>, ohad@...ery.com,
        bjorn.andersson@...aro.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 10/18] rpmsg: glink: Add support for TX intents



On 8/16/2017 10:49 PM, Sricharan R wrote:
> Intents are nothing but pre-allocated buffers of
> appropriate size that are allocated on the local
> side and communicated to the remote side and the
> remote stores the list of intent ids that it is
> informed.
>
> Later when remote side is intenting to send data,
> it picks up a right intent (based on the size) and
> sends the data buffer and the intent id. Local side
> receives the data and copies it to the local intent
> buffer.
>
> The whole idea is to avoid stalls on the transport
> for allocating memory, used for copy based transports.
>
> When the remote request to allocate buffers using
> CMD_RX_INTENT_REQ, we allocate buffers of requested
> size, store the buffer id locally and also communicate
> the intent id to the remote.
>
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>   drivers/rpmsg/qcom_glink_native.c | 161 +++++++++++++++++++++++++++++++++++++-
>   drivers/rpmsg/qcom_glink_native.h |   3 +-
>   drivers/rpmsg/qcom_glink_rpm.c    |   3 +-
>   drivers/rpmsg/qcom_glink_smem.c   |   5 +-
>   4 files changed, 167 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index acf5558..cbc9f9e 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -60,6 +60,25 @@ struct glink_defer_cmd {
>   };
>   
>   /**
> + * RX intent
> + *
> + * data: pointer to the data (may be NULL for zero-copy)
> + * id: remote or local intent ID
> + * size: size of the original intent (do not modify)
> + * reuse: To mark if the intent can be reused after first use
> + * in_use: To mark if intent is already in use for the channel
> + * offset: next write offset (initially 0)
> + */
> +struct glink_core_rx_intent {
> +	void *data;
> +	u32 id;
> +	size_t size;
> +	bool reuse;
> +	bool in_use;
> +	u32 offset;
> +};
> +
> +/**
>    * struct glink_rpm - driver context, relates to one remote subsystem
>    * @dev:	reference to the associated struct device
>    * @doorbell:	"rpm_hlos" ipc doorbell
> @@ -116,6 +135,8 @@ enum {
>    * @name:	unique channel name/identifier
>    * @lcid:	channel id, in local space
>    * @rcid:	channel id, in remote space
> + * @intent_lock: lock for protection of @liids
> + * @liids:	idr of all local intents
>    * @buf:	receive buffer, for gathering fragments
>    * @buf_offset:	write offset in @buf
>    * @buf_size:	size of current @buf
> @@ -136,6 +157,9 @@ struct glink_channel {
>   	unsigned int lcid;
>   	unsigned int rcid;
>   
> +	spinlock_t intent_lock;
> +	struct idr liids;
> +
>   	void *buf;
>   	int buf_offset;
>   	int buf_size;
> @@ -153,6 +177,9 @@ struct glink_channel {
>   #define RPM_CMD_OPEN			2
>   #define RPM_CMD_CLOSE			3
>   #define RPM_CMD_OPEN_ACK		4
> +#define RPM_CMD_INTENT			5
> +#define RPM_CMD_RX_INTENT_REQ		7
> +#define RPM_CMD_RX_INTENT_REQ_ACK	8
>   #define RPM_CMD_TX_DATA			9
>   #define RPM_CMD_CLOSE_ACK		11
>   #define RPM_CMD_TX_DATA_CONT		12
> @@ -177,6 +204,7 @@ static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
>   	init_completion(&channel->open_req);
>   	init_completion(&channel->open_ack);
>   
> +	idr_init(&channel->liids);

spinlock intent_lock initialization is missed ?
>   	kref_init(&channel->refcount);
>   
>   	return channel;
> @@ -187,6 +215,7 @@ static void qcom_glink_channel_release(struct kref *ref)
>   	struct glink_channel *channel = container_of(ref, struct glink_channel,
>   						     refcount);
>   
> +	idr_destroy(&channel->liids);

idr_destroy shouldn`t be covered by intent_lock ?

>   	kfree(channel->name);
>   	kfree(channel);
>   }
> @@ -423,6 +452,130 @@ static void qcom_glink_receive_version_ack(struct qcom_glink *glink,
>   	}
>   }
>   
> +/**
> + * qcom_glink_send_intent_req_ack() - convert an rx intent request ack cmd to
> +				      wire format and transmit
> + * @glink:	The transport to transmit on.
> + * @channel:	The glink channel
> + * @granted:	The request response to encode.
> + *
> + * Return: 0 on success or standard Linux error code.
> + */
> +static int qcom_glink_send_intent_req_ack(struct qcom_glink *glink,
> +					  struct glink_channel *channel,
> +					  bool granted)
> +{
> +	struct glink_msg msg;
> +
> +	msg.cmd = cpu_to_le16(RPM_CMD_RX_INTENT_REQ_ACK);
> +	msg.param1 = cpu_to_le16(channel->lcid);
> +	msg.param2 = cpu_to_le32(granted);
> +
> +	qcom_glink_tx(glink, &msg, sizeof(msg), NULL, 0, true);
> +
> +	return 0;
> +}
> +
> +/**
> + * tx_cmd_local_rx_intent() - convert an rx intent cmd to wire format and
> + *			   transmit

copy-paste mistake
> + * @glink:	The transport to transmit on.
> + * @channel:	The local channel
> + * @size:	The intent to pass on to remote.
> + *
> + * Return: 0 on success or standard Linux error code.
> + */
> +static int qcom_glink_advertise_intent(struct qcom_glink *glink,
> +				       struct glink_channel *channel,
> +				       struct glink_core_rx_intent *intent)
> +{
> +	struct command {
> +		u16 id;
> +		u16 lcid;
> +		u32 count;
> +		u32 size;
> +		u32 liid;
> +	} __packed;
> +	struct command cmd;
> +
> +	cmd.id = cpu_to_le16(RPM_CMD_INTENT);
> +	cmd.lcid = cpu_to_le16(channel->lcid);
> +	cmd.count = cpu_to_le32(1);
> +	cmd.size = cpu_to_le32(intent->size);
> +	cmd.liid = cpu_to_le32(intent->id);
> +
> +	qcom_glink_tx(glink, &cmd, sizeof(cmd), NULL, 0, true);
> +
> +	return 0;
> +}
> +
> +static struct glink_core_rx_intent *
> +qcom_glink_alloc_intent(struct qcom_glink *glink,
> +			struct glink_channel *channel,
> +			size_t size,
> +			bool reuseable)
> +{
> +	struct glink_core_rx_intent *intent;
> +	int ret;
> +	unsigned long flags;
> +
> +	intent = kzalloc(sizeof(*intent), GFP_KERNEL);
> +
> +	if (!intent)
> +		return NULL;
> +
> +	intent->data = kzalloc(size, GFP_KERNEL);
> +	if (!intent->data)
> +		return NULL;
> +
> +	spin_lock_irqsave(&channel->intent_lock, flags);
> +	ret = idr_alloc_cyclic(&channel->liids, intent, 1, -1, GFP_ATOMIC);
> +	if (ret < 0) {
> +		spin_unlock_irqrestore(&channel->intent_lock, flags);
> +		return NULL;
> +	}
> +	spin_unlock_irqrestore(&channel->intent_lock, flags);
> +
> +	intent->id = ret;
> +	intent->size = size;
> +	intent->reuse = reuseable;
> +
> +	return intent;
> +}
> +
> +/**
> + * glink_core_rx_cmd_remote_rx_intent_req() - Receive a request for rx_intent
> + *					    from remote side

copy-paste mistake
> + * if_ptr:      Pointer to the transport interface
> + * rcid:	Remote channel ID
> + * size:	size of the intent
> + *
> + * The function searches for the local channel to which the request for
> + * rx_intent has arrived and allocates and notifies the remote back
> + */
> +static void qcom_glink_handle_intent_req(struct qcom_glink *glink,
> +					 u32 cid, size_t size)
> +{
> +	struct glink_core_rx_intent *intent;
> +	struct glink_channel *channel;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&glink->idr_lock, flags);
> +	channel = idr_find(&glink->rcids, cid);
> +	spin_unlock_irqrestore(&glink->idr_lock, flags);
> +
> +	if (!channel) {
> +		pr_err("%s channel not found for cid %d\n", __func__, cid);
> +		return;
> +	}
> +
> +	intent = qcom_glink_alloc_intent(glink, channel, size, false);
> +	if (intent)
> +		qcom_glink_advertise_intent(glink, channel, intent);
> +
> +	qcom_glink_send_intent_req_ack(glink, channel, !!intent);
> +}
> +
>   static int qcom_glink_rx_defer(struct qcom_glink *glink, size_t extra)
>   {
>   	struct glink_defer_cmd *dcmd;
> @@ -585,6 +738,7 @@ static irqreturn_t qcom_glink_native_intr(int irq, void *data)
>   		case RPM_CMD_VERSION_ACK:
>   		case RPM_CMD_CLOSE:
>   		case RPM_CMD_CLOSE_ACK:
> +		case RPM_CMD_RX_INTENT_REQ:
>   			ret = qcom_glink_rx_defer(glink, 0);
>   			break;
>   		case RPM_CMD_OPEN_ACK:
> @@ -1002,6 +1156,9 @@ static void qcom_glink_work(struct work_struct *work)
>   		case RPM_CMD_CLOSE_ACK:
>   			qcom_glink_rx_close_ack(glink, param1);
>   			break;
> +		case RPM_CMD_RX_INTENT_REQ:
> +			qcom_glink_handle_intent_req(glink, param1, param2);
> +			break;
>   		default:
>   			WARN(1, "Unknown defer object %d\n", cmd);
>   			break;
> @@ -1014,7 +1171,8 @@ static void qcom_glink_work(struct work_struct *work)
>   struct qcom_glink *qcom_glink_native_probe(struct device *dev,
>   					   unsigned long features,
>   					   struct qcom_glink_pipe *rx,
> -					   struct qcom_glink_pipe *tx)
> +					   struct qcom_glink_pipe *tx,
> +					   bool intentless)
>   {
>   	int irq;
>   	int ret;
> @@ -1029,6 +1187,7 @@ struct qcom_glink *qcom_glink_native_probe(struct device *dev,
>   	glink->rx_pipe = rx;
>   
>   	glink->features = features;
> +	glink->intentless = intentless;
>   
>   	mutex_init(&glink->tx_lock);
>   	spin_lock_init(&glink->rx_lock);
> diff --git a/drivers/rpmsg/qcom_glink_native.h b/drivers/rpmsg/qcom_glink_native.h
> index f418787..d7538c3 100644
> --- a/drivers/rpmsg/qcom_glink_native.h
> +++ b/drivers/rpmsg/qcom_glink_native.h
> @@ -37,7 +37,8 @@ struct qcom_glink_pipe {
>   struct qcom_glink *qcom_glink_native_probe(struct device *dev,
>   					   unsigned long features,
>   					   struct qcom_glink_pipe *rx,
> -					   struct qcom_glink_pipe *tx);
> +					   struct qcom_glink_pipe *tx,
> +					   bool intentless);
>   void qcom_glink_native_remove(struct qcom_glink *glink);
>   
>   #endif
> diff --git a/drivers/rpmsg/qcom_glink_rpm.c b/drivers/rpmsg/qcom_glink_rpm.c
> index 7d039cd..5a86e08 100644
> --- a/drivers/rpmsg/qcom_glink_rpm.c
> +++ b/drivers/rpmsg/qcom_glink_rpm.c
> @@ -305,7 +305,8 @@ static int glink_rpm_probe(struct platform_device *pdev)
>   	glink = qcom_glink_native_probe(&pdev->dev,
>   					0,
>   					&rx_pipe->native,
> -					&tx_pipe->native);
> +					&tx_pipe->native,
> +					true);
>   	if (IS_ERR(glink))
>   		return PTR_ERR(glink);
>   
> diff --git a/drivers/rpmsg/qcom_glink_smem.c b/drivers/rpmsg/qcom_glink_smem.c
> index 496a5e3..e792895 100644
> --- a/drivers/rpmsg/qcom_glink_smem.c
> +++ b/drivers/rpmsg/qcom_glink_smem.c
> @@ -278,8 +278,9 @@ struct qcom_glink *qcom_glink_smem_register(struct device *parent,
>   	*tx_pipe->head = 0;
>   
>   	glink = qcom_glink_native_probe(dev,
> -					GLINK_FEATURE_TRACER_PKT,
> -					&rx_pipe->native, &tx_pipe->native);
> +					GLINK_FEATURE_INTENT_REUSE,
> +					&rx_pipe->native, &tx_pipe->native,
> +					false);
>   	if (IS_ERR(glink)) {
>   		ret = PTR_ERR(glink);
>   		goto err_put_dev;

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