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Let's convert the BAM DMA driver to using the high-priority variant of the BH workqueue. [Vinod: suggested using the BG workqueue instead of the regular one running in process context] Suggested-by: Vinod Koul Reviewed-by: Dmitry Baryshkov Reviewed-by: Bjorn Andersson Signed-off-by: Bartosz Golaszewski Signed-off-by: Bartosz Golaszewski --- Tested with the Qualcomm Crypto Engine with no impact on stability or performance (according to cryptsetup benchmark). Changes in v2: - Use the high-priority BH workqueue - Link to v1: https://lore.kernel.org/all/20251106-qcom-bam-dma-refactor-v1= -0-0e2baaf3d81a@linaro.org/ --- drivers/dma/qcom/bam_dma.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c index bcd8de9a9a12621a36b49c31bff96f474468be06..509d9296f6d7ef7662325e39fa1= 2b6db45badbec 100644 --- a/drivers/dma/qcom/bam_dma.c +++ b/drivers/dma/qcom/bam_dma.c @@ -42,6 +42,7 @@ #include #include #include +#include =20 #include "../dmaengine.h" #include "../virt-dma.h" @@ -397,8 +398,8 @@ struct bam_device { struct clk *bamclk; int irq; =20 - /* dma start transaction tasklet */ - struct tasklet_struct task; + /* dma start transaction workqueue */ + struct work_struct work; }; =20 /** @@ -869,7 +870,7 @@ static u32 process_channel_irqs(struct bam_device *bdev) /* * if complete, process cookie. Otherwise * push back to front of desc_issued so that - * it gets restarted by the tasklet + * it gets restarted by the work queue. */ if (!async_desc->num_desc) { vchan_cookie_complete(&async_desc->vd); @@ -899,9 +900,9 @@ static irqreturn_t bam_dma_irq(int irq, void *data) =20 srcs |=3D process_channel_irqs(bdev); =20 - /* kick off tasklet to start next dma transfer */ + /* kick off the work queue to start next dma transfer */ if (srcs & P_IRQ) - tasklet_schedule(&bdev->task); + queue_work(system_bh_highpri_wq, &bdev->work); =20 ret =3D pm_runtime_get_sync(bdev->dev); if (ret < 0) @@ -1097,14 +1098,14 @@ static void bam_start_dma(struct bam_chan *bchan) } =20 /** - * dma_tasklet - DMA IRQ tasklet - * @t: tasklet argument (bam controller structure) + * bam_dma_work() - DMA interrupt work queue callback + * @work: work queue struct embedded in the BAM controller device struct * * Sets up next DMA operation and then processes all completed transactions */ -static void dma_tasklet(struct tasklet_struct *t) +static void bam_dma_work(struct work_struct *work) { - struct bam_device *bdev =3D from_tasklet(bdev, t, task); + struct bam_device *bdev =3D from_work(bdev, work, work); struct bam_chan *bchan; unsigned int i; =20 @@ -1117,14 +1118,13 @@ static void dma_tasklet(struct tasklet_struct *t) if (!list_empty(&bchan->vc.desc_issued) && !IS_BUSY(bchan)) bam_start_dma(bchan); } - } =20 /** * bam_issue_pending - starts pending transactions * @chan: dma channel * - * Calls tasklet directly which in turn starts any pending transactions + * Calls work queue directly which in turn starts any pending transactions */ static void bam_issue_pending(struct dma_chan *chan) { @@ -1292,14 +1292,14 @@ static int bam_dma_probe(struct platform_device *pd= ev) if (ret) goto err_disable_clk; =20 - tasklet_setup(&bdev->task, dma_tasklet); + INIT_WORK(&bdev->work, bam_dma_work); =20 bdev->channels =3D devm_kcalloc(bdev->dev, bdev->num_channels, sizeof(*bdev->channels), GFP_KERNEL); =20 if (!bdev->channels) { ret =3D -ENOMEM; - goto err_tasklet_kill; + goto err_workqueue_cancel; } =20 /* allocate and initialize channels */ @@ -1364,8 +1364,8 @@ static int bam_dma_probe(struct platform_device *pdev) err_bam_channel_exit: for (i =3D 0; i < bdev->num_channels; i++) tasklet_kill(&bdev->channels[i].vc.task); -err_tasklet_kill: - tasklet_kill(&bdev->task); +err_workqueue_cancel: + cancel_work_sync(&bdev->work); err_disable_clk: clk_disable_unprepare(bdev->bamclk); =20 @@ -1399,7 +1399,7 @@ static void bam_dma_remove(struct platform_device *pd= ev) bdev->channels[i].fifo_phys); } =20 - tasklet_kill(&bdev->task); + cancel_work_sync(&bdev->work); =20 clk_disable_unprepare(bdev->bamclk); } --- base-commit: 970d7fed472fd561d12773ff445497f847b7161d change-id: 20251218-bam-dma-bh-workqueue-0d80ec0b6392 Best regards, --=20 Bartosz Golaszewski