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mhi: core: Prevent doorbell with invalid tre

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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: Sriharsha Allenki <sallenki@codeaurora.org>
This commit is contained in:
Sriharsha Allenki 2021-06-15 15:38:33 +05:30
parent 34bd57b55a
commit 50b98084f0
1 changed files with 18 additions and 17 deletions
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35
drivers/bus/mhi/core/mhi_main.c
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@ -1,5 +1,5 @@
// 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);
@ -587,12 +575,25 @@ 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);
mhi_ring_chan_db(mhi_cntrl, mhi_chan);
read_unlock_bh(&mhi_chan->lock);
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);
return 0;