Re: [PATCH 4/7] dma: mcf-edma: Fix interrupt handler for 64 DMA channels

Frank Li
2025-11-24T16:09:17Z

On Mon, Nov 24, 2025 at 01:50:25PM +0100, Jean-Michel Hautbois wrote:
> Fix the DMA completion interrupt handler to properly handle all 64
> channels on MCF54418 ColdFire processors.
>
> The previous code used BIT(ch) to test interrupt status bits, which
> causes undefined behavior on 32-bit architectures when ch >= 32 because
> unsigned long is 32 bits and the shift would exceed the type width.
>
> Replace with bitmap_from_u64() and for_each_set_bit() which correctly
> handle 64-bit values on 32-bit systems by using a proper bitmap
> representation.
>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
> ---
> drivers/dma/mcf-edma-main.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/mcf-edma-main.c b/drivers/dma/mcf-edma-main.c
> index 8a7c1787adb1f66f3b6729903635b072218afad1..dd64f50f2b0a70a4664b03c7d6a23e74c9bcd7ae 100644
> --- a/drivers/dma/mcf-edma-main.c
> +++ b/drivers/dma/mcf-edma-main.c
> @@ -18,7 +18,8 @@ static irqreturn_t mcf_edma_tx_handler(int irq, void *dev_id)
> {
> struct fsl_edma_engine *mcf_edma = dev_id;
> struct edma_regs *regs = &mcf_edma->regs;
> - unsigned int ch;
> + unsigned long ch;

channel number max value is 63. unsigned int should be enough.

Frank
> + DECLARE_BITMAP(status_mask, 64);
> u64 intmap;
>
> intmap = ioread32(regs->inth);
> @@ -27,11 +28,11 @@ static irqreturn_t mcf_edma_tx_handler(int irq, void *dev_id)
> if (!intmap)
> return IRQ_NONE;
>
> - for (ch = 0; ch < mcf_edma->n_chans; ch++) {
> - if (intmap & BIT(ch)) {
> - iowrite8(EDMA_MASK_CH(ch), regs->cint);
> - fsl_edma_tx_chan_handler(&mcf_edma->chans[ch]);
> - }
> + bitmap_from_u64(status_mask, intmap);
> +
> + for_each_set_bit(ch, status_mask, mcf_edma->n_chans) {
> + iowrite8(EDMA_MASK_CH(ch), regs->cint);
> + fsl_edma_tx_chan_handler(&mcf_edma->chans[ch]);
> }
>
> return IRQ_HANDLED;
>
> --
> 2.39.5
>