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Mon, 10 Aug 2026 11:13:11 -0700 (PDT) From: Allen Pais To: Vinod Koul , Frank Li Cc: Allen Pais , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Kees Cook Subject: [PATCH v3 26/34] dmaengine: mpc512x: route callbacks via channel BH Date: Mon, 10 Aug 2026 11:09:27 -0700 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Schedule per-channel BH work for completions and process callbacks there, leaving the controller tasklet for IRQ/error handling. Signed-off-by: Allen Pais --- drivers/dma/mpc512x_dma.c | 74 +++++++++++++++++++++++++-------------- 1 file changed, 47 insertions(+), 27 deletions(-) diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c index 0adc8e01057e..19e0b2f1b2aa 100644 --- a/drivers/dma/mpc512x_dma.c +++ b/drivers/dma/mpc512x_dma.c @@ -372,45 +372,47 @@ static irqreturn_t mpc_dma_irq(int irq, void *data) return IRQ_HANDLED; } -/* process completed descriptors */ -static void mpc_dma_process_completed(struct mpc_dma *mdma) +static void mpc_dma_process_chan_completed(struct mpc_dma_chan *mchan) { dma_cookie_t last_cookie = 0; - struct mpc_dma_chan *mchan; struct mpc_dma_desc *mdesc; struct dma_async_tx_descriptor *desc; unsigned long flags; LIST_HEAD(list); - int i; - for (i = 0; i < mdma->dma.chancnt; i++) { - mchan = &mdma->channels[i]; + /* Get all completed descriptors */ + spin_lock_irqsave(&mchan->lock, flags); + if (!list_empty(&mchan->completed)) + list_splice_tail_init(&mchan->completed, &list); + spin_unlock_irqrestore(&mchan->lock, flags); - /* Get all completed descriptors */ - spin_lock_irqsave(&mchan->lock, flags); - if (!list_empty(&mchan->completed)) - list_splice_tail_init(&mchan->completed, &list); - spin_unlock_irqrestore(&mchan->lock, flags); + if (list_empty(&list)) + return; - if (list_empty(&list)) - continue; + /* Execute callbacks and run dependencies */ + list_for_each_entry(mdesc, &list, node) { + desc = &mdesc->desc; - /* Execute callbacks and run dependencies */ - list_for_each_entry(mdesc, &list, node) { - desc = &mdesc->desc; + dmaengine_desc_get_callback_invoke(desc, NULL); - dmaengine_desc_get_callback_invoke(desc, NULL); + last_cookie = desc->cookie; + dma_run_dependencies(desc); + } - last_cookie = desc->cookie; - dma_run_dependencies(desc); - } + /* Free descriptors */ + spin_lock_irqsave(&mchan->lock, flags); + list_splice_tail_init(&list, &mchan->free); + mchan->chan.completed_cookie = last_cookie; + spin_unlock_irqrestore(&mchan->lock, flags); +} - /* Free descriptors */ - spin_lock_irqsave(&mchan->lock, flags); - list_splice_tail_init(&list, &mchan->free); - mchan->chan.completed_cookie = last_cookie; - spin_unlock_irqrestore(&mchan->lock, flags); - } +/* process completed descriptors */ +static void mpc_dma_process_completed(struct mpc_dma *mdma) +{ + int i; + + for (i = 0; i < mdma->dma.chancnt; i++) + mpc_dma_process_chan_completed(&mdma->channels[i]); } /* DMA Tasklet */ @@ -419,6 +421,7 @@ static void mpc_dma_tasklet(struct tasklet_struct *t) struct mpc_dma *mdma = from_tasklet(mdma, t, tasklet); unsigned long flags; uint es; + int i; spin_lock_irqsave(&mdma->error_status_lock, flags); es = mdma->error_status; @@ -453,7 +456,21 @@ static void mpc_dma_tasklet(struct tasklet_struct *t) dev_err(mdma->dma.dev, "- Destination Bus Error\n"); } - mpc_dma_process_completed(mdma); + for (i = 0; i < mdma->dma.chancnt; i++) { + struct mpc_dma_chan *mchan = &mdma->channels[i]; + + spin_lock_irqsave(&mchan->lock, flags); + if (!list_empty(&mchan->completed)) + dmaengine_schedule_bh(&mchan->chan); + spin_unlock_irqrestore(&mchan->lock, flags); + } +} + +static void mpc_dma_chan_bh(struct dma_chan *chan) +{ + struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan); + + mpc_dma_process_chan_completed(mchan); } /* Submit descriptor to hardware */ @@ -551,6 +568,8 @@ static void mpc_dma_free_chan_resources(struct dma_chan *chan) unsigned long flags; LIST_HEAD(descs); + dmaengine_kill_bh(&mchan->chan); + spin_lock_irqsave(&mchan->lock, flags); /* Channel must be idle */ @@ -1007,6 +1026,7 @@ static int mpc_dma_probe(struct platform_device *op) INIT_LIST_HEAD(&mchan->completed); spin_lock_init(&mchan->lock); + dmaengine_init_bh(&mchan->chan, mpc_dma_chan_bh); list_add_tail(&mchan->chan.device_node, &dma->channels); } -- 2.43.0