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Commit 0c3c8033 authored by Sujeev Dias's avatar Sujeev Dias Committed by Gerrit - the friendly Code Review server
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mhi_bus: core: add support for pre-allocating buffers for DL channels 



Like other transport layers such as rpmsg, add support to
pre-allocate buffers for DL data path. So, client drivers do not
need to drastically change their implementation when switching to
a different transport layer.

CRs-Fixed: 2221013
Change-Id: I2e10089295c003a43d1b6f46c7c877a5321f5bc9
Signed-off-by: default avatarSujeev Dias <sdias@codeaurora.org>
parent ee84a2e4

Documentation/devicetree/bindings/bus/mhi.txt

+3 −0
Original line number Diff line number Diff line
@@ -52,6 +52,9 @@ Main node properties: 
		the data pipe. Not involved in active data transfer.

		BIT(2) : Must switch to doorbell mode whenever MHI M0 state

		transition happens.

		BIT(3) : MHI bus driver pre-allocate buffer for this channel.

		If set, clients not allowed to queue buffers. Valid only for DL

		direction.



- mhi,chan-names

  Usage: required

drivers/bus/mhi/core/mhi_init.c

+10 −0
Original line number Diff line number Diff line
@@ -823,6 +823,16 @@ static int of_parse_ch_cfg(struct mhi_controller *mhi_cntrl, 
		mhi_chan->offload_ch = !!(bit_cfg & MHI_CH_CFG_BIT_OFFLOAD_CH);

		mhi_chan->db_cfg.reset_req =

			!!(bit_cfg & MHI_CH_CFG_BIT_DBMODE_RESET_CH);

		mhi_chan->pre_alloc = !!(bit_cfg & MHI_CH_CFG_BIT_PRE_ALLOC);



		if (mhi_chan->pre_alloc &&

		    (mhi_chan->dir != DMA_FROM_DEVICE ||

		     mhi_chan->xfer_type != MHI_XFER_BUFFER))

			goto error_chan_cfg;



		/* if mhi host allocate the buffers then client cannot queue */

		if (mhi_chan->pre_alloc)

			mhi_chan->queue_xfer = mhi_queue_nop;



		ret = of_property_read_string_index(of_node, "mhi,chan-names",

						    i, &mhi_chan->name);

drivers/bus/mhi/core/mhi_internal.h

+2 −0
Original line number Diff line number Diff line
@@ -339,6 +339,7 @@ enum MHI_CH_CFG { 
#define MHI_CH_CFG_BIT_LPM_NOTIFY BIT(0) /* require LPM notification */

#define MHI_CH_CFG_BIT_OFFLOAD_CH BIT(1) /* satellite mhi devices */

#define MHI_CH_CFG_BIT_DBMODE_RESET_CH BIT(2) /* require db mode to reset */

#define MHI_CH_CFG_BIT_PRE_ALLOC BIT(3) /* host allocate buffers for DL */



enum MHI_EV_CFG {

	MHI_EV_CFG_ELEMENTS = 0,
@@ -565,6 +566,7 @@ struct mhi_chan { 
	bool lpm_notify;

	bool configured;

	bool offload_ch;

	bool pre_alloc;

	/* functions that generate the transfer ring elements */

	int (*gen_tre)(struct mhi_controller *, struct mhi_chan *, void *,

		       void *, size_t, enum MHI_FLAGS);

drivers/bus/mhi/core/mhi_main.c

+54 −0
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ 
#include <linux/mhi.h>

#include "mhi_internal.h"



static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,

				    struct mhi_chan *mhi_chan);



int __must_check mhi_read_reg(struct mhi_controller *mhi_cntrl,

			      void __iomem *base,

			      u32 offset,
@@ -661,6 +664,22 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl, 
				mhi_cntrl->wake_put(mhi_cntrl, false);

				read_unlock_bh(&mhi_cntrl->pm_lock);

			}



			/*

			 * recycle the buffer if buffer is pre-allocated,

			 * if there is error, not much we can do apart from

			 * dropping the packet

			 */

			if (mhi_chan->pre_alloc) {

				if (mhi_queue_buf(mhi_chan->mhi_dev, mhi_chan,

						  buf_info->cb_buf,

						  buf_info->len, MHI_EOT)) {

					MHI_ERR(

						"Error recycling buffer for chan:%d\n",

						mhi_chan->chan);

					kfree(buf_info->cb_buf);

				}

			}

		};

		break;

	} /* CC_EOT */
@@ -1086,6 +1105,32 @@ static int __mhi_prepare_channel(struct mhi_controller *mhi_cntrl, 
	mhi_cntrl->wake_put(mhi_cntrl, false);

	read_unlock_bh(&mhi_cntrl->pm_lock);



	/* pre allocate buffer for xfer ring */

	if (mhi_chan->pre_alloc) {

		struct mhi_device *mhi_dev = mhi_chan->mhi_dev;

		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,

						       &mhi_chan->tre_ring);



		while (nr_el--) {

			void *buf;



			buf = kmalloc(MHI_MAX_MTU, GFP_KERNEL);

			if (!buf) {

				ret = -ENOMEM;

				goto error_pre_alloc;

			}



			ret = mhi_queue_buf(mhi_dev, mhi_chan, buf, MHI_MAX_MTU,

					    MHI_EOT);

			if (ret) {

				MHI_ERR("Chan:%d error queue buffer\n",

					mhi_chan->chan);

				kfree(buf);

				goto error_pre_alloc;

			}

		}

	}



	mutex_unlock(&mhi_chan->mutex);



	MHI_LOG("Chan:%d successfully moved to start state\n", mhi_chan->chan);
@@ -1104,6 +1149,12 @@ static int __mhi_prepare_channel(struct mhi_controller *mhi_cntrl, 
error_init_chan:

	mutex_unlock(&mhi_chan->mutex);



	return ret;



error_pre_alloc:

	mutex_unlock(&mhi_chan->mutex);

	__mhi_unprepare_channel(mhi_cntrl, mhi_chan);



	return ret;

}
@@ -1169,6 +1220,9 @@ void mhi_reset_chan(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan) 
				 buf_info->len, buf_info->dir);

		mhi_del_ring_element(mhi_cntrl, buf_ring);

		mhi_del_ring_element(mhi_cntrl, tre_ring);



		if (mhi_chan->pre_alloc)

			kfree(buf_info->cb_buf);

	}



	read_unlock_bh(&mhi_cntrl->pm_lock);