Hi Tony,
On 22-10-19, 07:55, Tony Lindgren wrote:
Patch subject should reflect the patch changes not the fix. The patch
title here is not telling me anything about the change below. Pls
consider updating the title.
> The first dma call done by musb_ep_program() must wait if cppi41 is PM
> runtime suspended. Otherwise musb_ep_program() continues with other
> non-dma packets before the DMA transfer is started causing at least ftdi
> uarts to fail to receive data.
>
> Let's fix the issue by waking up cppi41 with PM runtime calls added to
> cppi41_dma_prep_slave_sg() and return NULL if still idled. This way we
> have musb_ep_program() continue with PIO until cppi41 is awake.
>
> Fixes: fdea2d09b997 ("dmaengine: cppi41: Add basic PM runtime support")
Cc stable?
> Cc: Bin Liu <b-liu@xxxxxx>
> Cc: giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx
> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Sebastian Reichel <sre@xxxxxxxxxx>
> Cc: Skvortsov <andrej.skvortzov@xxxxxxxxx>
> Reported-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
> drivers/dma/ti/cppi41.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/ti/cppi41.c b/drivers/dma/ti/cppi41.c
> --- a/drivers/dma/ti/cppi41.c
> +++ b/drivers/dma/ti/cppi41.c
> @@ -586,9 +586,22 @@ static struct dma_async_tx_descriptor *cppi41_dma_prep_slave_sg(
> enum dma_transfer_direction dir, unsigned long tx_flags, void *context)
> {
> struct cppi41_channel *c = to_cpp41_chan(chan);
> + struct dma_async_tx_descriptor *txd = NULL;
> + struct cppi41_dd *cdd = c->cdd;
> struct cppi41_desc *d;
> struct scatterlist *sg;
> unsigned int i;
> + int error;
> +
> + error = pm_runtime_get(cdd->ddev.dev);
> + if (error < 0) {
> + pm_runtime_put_noidle(cdd->ddev.dev);
> +
> + return NULL;
> + }
> +
> + if (cdd->is_suspended)
> + goto err_out_not_ready;
>
> d = c->desc;
> for_each_sg(sgl, sg, sg_len, i) {
> @@ -611,7 +624,13 @@ static struct dma_async_tx_descriptor *cppi41_dma_prep_slave_sg(
> d++;
> }
>
> - return &c->txd;
> + txd = &c->txd;
> +
> +err_out_not_ready:
> + pm_runtime_mark_last_busy(cdd->ddev.dev);
> + pm_runtime_put_autosuspend(cdd->ddev.dev);
> +
> + return txd;
> }
>
> static void cppi41_compute_td_desc(struct cppi41_desc *d)
> --
> 2.23.0
--
~Vinod
