Hi Biju,
On Thu, Jul 21, 2022 at 4:49 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> Some on-chip peripheral modules(for eg:- rspi) on RZ/G2L SoC
> use the same signal for both interrupt and DMA transfer requests.
> The signal works as a DMA transfer request signal by setting
> DMARS, and subsequent interrupt requests to the interrupt controller
> are masked.
>
> We can re-enable the interrupt by clearing the DMARS.
>
> This patch adds device_synchronize callback for clearing
> DMARS and thereby allowing DMA consumers to switch to
> interrupt mode.
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> ---
> v2->v3:
> * Fixed commit description
> * Added check if the DMA operation has been completed or terminated,
> and wait (sleep) if needed.
Thanks for the uodate!
> --- a/drivers/dma/sh/rz-dmac.c
> +++ b/drivers/dma/sh/rz-dmac.c
> @@ -12,6 +12,7 @@
> #include <linux/dma-mapping.h>
> #include <linux/dmaengine.h>
> #include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> #include <linux/list.h>
> #include <linux/module.h>
> #include <linux/of.h>
> @@ -630,6 +631,21 @@ static void rz_dmac_virt_desc_free(struct virt_dma_desc *vd)
> */
> }
>
> +static void rz_dmac_device_synchronize(struct dma_chan *chan)
> +{
> + struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
> + struct rz_dmac *dmac = to_rz_dmac(chan->device);
> + u32 chstat;
> + int ret;
> +
> + ret = read_poll_timeout(rz_dmac_ch_readl, chstat, !(chstat & CHSTAT_EN),
> + 10, 1000, false, channel, CHSTAT, 1);
Isn't 1000 µs = 1 ms a bit short?
IIUIC, I can submit a DMA operation for transfering a 64 KiB (or larger)
block, and call dmaengine_synchronize() immediately after that?
> + if (ret < 0)
> + dev_warn(dmac->dev, "DMA Timeout");
> +
> + rz_dmac_set_dmars_register(dmac, channel->index, 0);
> +}
> +
> /*
> * -----------------------------------------------------------------------------
> * IRQ handling
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
