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

[Rosen Penev]

On Wed, Sep 16, 2026 at 8:25 PM Frank Li <Frank.li@xxxxxxxxxxx> wrote:
>
> On Wed, Sep 16, 2026 at 03:41:56PM -0700, Rosen Penev wrote:
> > 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.
>
> > 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 <rosenp@xxxxxxxxx>
> > ---
> >  v2: resend.
>
> If resend, don't pump version.
>
> Frank
> >  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.
>
> >       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
> >