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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Sricharan R <sricharan@codeaurora.org>,
        Vinod Koul <vkoul@kernel.org>
Subject: [PATCH 4.19 89/90] dmaengine: qcom: bam_dma: Fix completed descriptors count
Date:   Mon,  8 Jul 2019 17:13:56 +0200
Message-Id: <20190708150527.042392553@linuxfoundation.org>
In-Reply-To: <20190708150521.829733162@linuxfoundation.org>
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From: Sricharan R <sricharan@codeaurora.org>

commit f6034225442c4a87906d36e975fd9e99a8f95487 upstream.

One space is left unused in circular FIFO to differentiate
'full' and 'empty' cases. So take that in to account while
counting for the descriptors completed.

Fixes the issue reported here,
	https://lkml.org/lkml/2019/6/18/669

Cc: stable@vger.kernel.org
Reported-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/qcom/bam_dma.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -808,6 +808,9 @@ static u32 process_channel_irqs(struct b
 		/* Number of bytes available to read */
 		avail = CIRC_CNT(offset, bchan->head, MAX_DESCRIPTORS + 1);
 
+		if (offset < bchan->head)
+			avail--;
+
 		list_for_each_entry_safe(async_desc, tmp,
 					 &bchan->desc_list, desc_node) {
 			/* Not enough data to read */