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Commit 50b98084 authored by Sriharsha Allenki's avatar Sriharsha Allenki
Browse files

mhi: core: Prevent doorbell with invalid tre 



In the cases of HW accelerated channels, there
is a possibility that the db_mode has changed while
a queue is in progress. This can happen when
mhi_queue_dma is scheduled out and an OOB event
is parsed.
Fix this by determining whether to ring the
doorbell or not without releasing the lock to
ensure persistence of db_mode.

Change-Id: I586937057ff0b3329813c10d5f4337a2df887fd1
Signed-off-by: default avatarSriharsha Allenki <sallenki@codeaurora.org>
parent 34bd57b5

drivers/bus/mhi/core/mhi_main.c

+18 −17
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2018-2020, The Linux Foundation. All rights reserved. */

/* Copyright (c) 2018-2021, The Linux Foundation. All rights reserved. */



#include <linux/debugfs.h>

#include <linux/device.h>
@@ -558,18 +558,6 @@ int mhi_queue_dma(struct mhi_device *mhi_dev, 
		mhi_tre->dword[0] =

			MHI_RSCTRE_DATA_DWORD0(buf_ring->wp - buf_ring->base);

		mhi_tre->dword[1] = MHI_RSCTRE_DATA_DWORD1;

		/*

		 * on RSC channel IPA HW has a minimum credit requirement before

		 * switching to DB mode

		 */

		n_free_tre = mhi_get_no_free_descriptors(mhi_dev,

				DMA_FROM_DEVICE);

		n_queued_tre = tre_ring->elements - n_free_tre;

		read_lock_bh(&mhi_chan->lock);

		if (mhi_chan->db_cfg.db_mode &&

				n_queued_tre < MHI_RSC_MIN_CREDITS)

			ring_db = false;

		read_unlock_bh(&mhi_chan->lock);

	} else {

		mhi_tre->ptr = MHI_TRE_DATA_PTR(buf_info->p_addr);

		mhi_tre->dword[0] = MHI_TRE_DATA_DWORD0(buf_info->len);
@@ -587,11 +575,24 @@ int mhi_queue_dma(struct mhi_device *mhi_dev, 
	if (mhi_chan->dir == DMA_TO_DEVICE)

		atomic_inc(&mhi_cntrl->pending_pkts);



	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)) && ring_db) {

	read_lock_bh(&mhi_chan->lock);

	if (mhi_chan->xfer_type == MHI_XFER_RSC_DMA) {

		/*

		 * on RSC channel IPA HW has a minimum credit requirement before

		 * switching to DB mode

		 */

		n_free_tre = mhi_get_no_free_descriptors(mhi_dev,

				DMA_FROM_DEVICE);

		n_queued_tre = tre_ring->elements - n_free_tre;

		if (mhi_chan->db_cfg.db_mode &&

				n_queued_tre < MHI_RSC_MIN_CREDITS)

			ring_db = false;

	}



	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)) && ring_db)

		mhi_ring_chan_db(mhi_cntrl, mhi_chan);



	read_unlock_bh(&mhi_chan->lock);

	}



	read_unlock_bh(&mhi_cntrl->pm_lock);