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Message-ID: <15c92c2f-71e7-f4fd-b90b-412ab53e5a25@pcs.com>
Date: Tue, 14 Nov 2023 13:22:06 +0100
From: Thomas Pfaff <tpfaff@....com>
To: <ludovic.desroches@...rochip.com>, <tudor.ambarus@...rochip.com>
CC: <nicolas.ferre@...rochip.com>, <vkoul@...nel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH RFC 1/2 stable-6.1] dmaengine: at_hdmac: get next dma transfer
from the right list
From: Thomas Pfaff <tpfaff@....com>
In kernel 6.1, atc_advance_work and atc_handle_error are checking for the
next dma transfer inside active list, but the descriptor is taken from the
queue instead.
Signed-off-by: Thomas Pfaff <tpfaff@....com>
---
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 858bd64f1313..68c1bfbefc5c 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -490,6 +490,27 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
}
}
+/**
+ * atc_start_next - start next pending transaction if any
+ * @atchan: channel where the transaction ended
+ *
+ * Called with atchan->lock held
+ */
+static void atc_start_next(struct at_dma_chan *atchan)
+{
+ struct at_desc *desc = NULL;
+
+ if (!list_empty(&atchan->active_list))
+ desc = atc_first_active(atchan);
+ else if (!list_empty(&atchan->queue)) {
+ desc = atc_first_queued(atchan);
+ list_move_tail(&desc->desc_node, &atchan->active_list);
+ }
+
+ if (desc)
+ atc_dostart(atchan, desc);
+}
+
/**
* atc_advance_work - at the end of a transaction, move forward
* @atchan: channel where the transaction ended
@@ -513,11 +534,7 @@ static void atc_advance_work(struct at_dma_chan *atchan)
/* advance work */
spin_lock_irqsave(&atchan->lock, flags);
- if (!list_empty(&atchan->active_list)) {
- desc = atc_first_queued(atchan);
- list_move_tail(&desc->desc_node, &atchan->active_list);
- atc_dostart(atchan, desc);
- }
+ atc_start_next(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
}
@@ -529,7 +546,6 @@ static void atc_advance_work(struct at_dma_chan *atchan)
static void atc_handle_error(struct at_dma_chan *atchan)
{
struct at_desc *bad_desc;
- struct at_desc *desc;
struct at_desc *child;
unsigned long flags;
@@ -543,11 +559,7 @@ static void atc_handle_error(struct at_dma_chan *atchan)
list_del_init(&bad_desc->desc_node);
/* Try to restart the controller */
- if (!list_empty(&atchan->active_list)) {
- desc = atc_first_queued(atchan);
- list_move_tail(&desc->desc_node, &atchan->active_list);
- atc_dostart(atchan, desc);
- }
+ atc_start_next(atchan);
/*
* KERN_CRITICAL may seem harsh, but since this only happens
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