Re: [PATCHv2] dmaengine: bestcomm: use platform machinery to get irq

On Wed, Sep 16, 2026 at 8:25 PM Frank Li [off-list ref] wrote:

On Wed, Sep 16, 2026 at 03:41:56PM -0700, Rosen Penev wrote:

quoted

platform_get_irq() avoids having to explicitly map and dispose of an irq
by having the platform_device machinery take care of it.

This requires replacing the device_node with a platform_device in the
bcom_eng struct so that platform_get_irq() can use it.

Conveniently, this also allows getting rid of of_node_get and
of_node_put as the platform_device machinery also handles that.

Replace the open-coded resource lookup, request_mem_region, ioremap and
the manual iounmap/release_mem_region cleanup in probe/remove with the
managed devm_platform_get_and_ioremap_resource() helper. This removes the

update commit message, no devm_platform_get_and_ioremap_resource() in patch.

quoted

now-unused error-unmap/release paths and simplifies the driver.

Adjust the goto labels in bcom_task_alloc to match what is being freed.

Signed-off-by: Rosen Penev <redacted>
---
 v2: resend.

If resend, don't pump version.

Frank

quoted

 drivers/dma/bestcomm/bestcomm.c            | 47 ++++++++--------------
 include/linux/fsl/bestcomm/bestcomm_priv.h |  2 +-
 2 files changed, 18 insertions(+), 31 deletions(-)

diff --git a/drivers/dma/bestcomm/bestcomm.c b/drivers/dma/bestcomm/bestcomm.c
index 241a91936fe8..1006030ff167 100644
--- a/drivers/dma/bestcomm/bestcomm.c
+++ b/drivers/dma/bestcomm/bestcomm.c

@@ -47,6 +47,7 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)
 {
      int i, tasknum = -1;
      struct bcom_task *tsk;
+     int irq;

      /* Don't try to do anything if bestcomm init failed */
      if (!bcom_eng)

@@ -67,30 +68,32 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)
      if (tasknum < 0)
              return NULL;

+     irq = platform_get_irq(bcom_eng->pdev, tasknum);
+     if (irq < 0)
+             goto err1;
+
      /* Allocate our structure */
      tsk = kzalloc(sizeof(struct bcom_task) + priv_size, GFP_KERNEL);
      if (!tsk)
-             goto error;
+             goto err1;

      tsk->tasknum = tasknum;
      if (priv_size)
              tsk->priv = (void*)tsk + sizeof(struct bcom_task);

      /* Get IRQ of that task */
-     tsk->irq = irq_of_parse_and_map(bcom_eng->ofnode, tsk->tasknum);
-     if (!tsk->irq)
-             goto error;
+     tsk->irq = irq;

      /* Init the BDs, if needed */
      if (bd_count) {
              tsk->cookie = kmalloc_array(bd_count, sizeof(void *),
                                          GFP_KERNEL);
              if (!tsk->cookie)
-                     goto error;
+                     goto err2;

              tsk->bd = bcom_sram_alloc(bd_count * bd_size, 4, &tsk->bd_pa);
              if (!tsk->bd)
-                     goto error;
+                     goto err3;
              memset_io(tsk->bd, 0x00, bd_count * bd_size);

              tsk->num_bd = bd_count;

@@ -99,17 +102,12 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)

      return tsk;

-error:
-     if (tsk) {
-             if (tsk->irq)
-                     irq_dispose_mapping(tsk->irq);
-             bcom_sram_free(tsk->bd);
-             kfree(tsk->cookie);
-             kfree(tsk);
-     }
-
+err3:
+     kfree(tsk->cookie);
+err2:
+     kfree(tsk);
+err1:
      bcom_eng->tdt[tasknum].stop = 0;
-

avoid unnecesary change.

There's nothing unnecessary about this. irq_dispose_mapping goes away.
bcom_sram_free is a mistake here. It's not reachable after
bcom_sram_alloc. This is much clearer to look at.

Moving bcom_sram_free removal to its own commit is pointless churn.

quoted

      return NULL;
 }
 EXPORT_SYMBOL_GPL(bcom_task_alloc);

@@ -125,7 +123,6 @@ bcom_task_free(struct bcom_task *tsk)
      bcom_eng->tdt[tsk->tasknum].stop  = 0;

      /* Free everything */
-     irq_dispose_mapping(tsk->irq);
      bcom_sram_free(tsk->bd);
      kfree(tsk->cookie);
      kfree(tsk);

@@ -377,16 +374,12 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
      if (IS_ERR(regs))
              return PTR_ERR(regs);

-     /* Get the bestcomm node */
-     of_node_get(op->dev.of_node);
-
      /* Prepare SRAM */
      ofn_sram = of_find_matching_node(NULL, mpc52xx_sram_ids);
      if (!ofn_sram) {
              printk(KERN_ERR DRIVER_NAME ": "
                      "No SRAM found in device tree\n");
-             rv = -ENODEV;
-             goto error_ofput;
+             return -ENODEV;
      }
      rv = bcom_sram_init(ofn_sram, DRIVER_NAME);
      of_node_put(ofn_sram);

@@ -394,7 +387,7 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
      if (rv) {
              printk(KERN_ERR DRIVER_NAME ": "
                      "Error in SRAM init\n");
-             goto error_ofput;
+             return rv;
      }

      /* Get a clean struct */

@@ -405,8 +398,7 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
      }

      /* Save the node */
-     bcom_eng->ofnode = op->dev.of_node;
-
+     bcom_eng->pdev = op;
      bcom_eng->regs = regs;
      bcom_eng->regs_base = res_bcom->start;

@@ -426,8 +418,6 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
      kfree(bcom_eng);
      bcom_eng = NULL;
      bcom_sram_cleanup();
-error_ofput:
-     of_node_put(op->dev.of_node);

      printk(KERN_ERR "DMA: MPC52xx BestComm init failed !\n");

@@ -443,9 +433,6 @@ static void mpc52xx_bcom_remove(struct platform_device *op)
      /* Cleanup SRAM */
      bcom_sram_cleanup();

-     /* Release the node */
-     of_node_put(bcom_eng->ofnode);
-
      /* Release memory */
      kfree(bcom_eng);
      bcom_eng = NULL;

diff --git a/include/linux/fsl/bestcomm/bestcomm_priv.h b/include/linux/fsl/bestcomm/bestcomm_priv.h
index 3b52f3ffbdf8..cddde7c74cb5 100644
--- a/include/linux/fsl/bestcomm/bestcomm_priv.h
+++ b/include/linux/fsl/bestcomm/bestcomm_priv.h

@@ -66,7 +66,7 @@ struct bcom_tdt {
  * This holds all info needed globaly to handle the engine
  */
 struct bcom_engine {
-     struct device_node              *ofnode;
+     struct platform_device          *pdev;
      struct mpc52xx_sdma __iomem     *regs;
      phys_addr_t                      regs_base;

--

2.55.0