From: Tony Lindgren tony@atomide.com
commit bacdcb6675e170bb2e8d3824da220e10274f42a7 upstream.
Yegor Yefremov yegorslists@googlemail.com reported that musb and ftdi uart can fail for the first open of the uart unless connected using a hub.
This is because 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") Reported-by: Yegor Yefremov yegorslists@googlemail.com Signed-off-by: Tony Lindgren tony@atomide.com Cc: stable@vger.kernel.org # v4.9+ Link: https://lore.kernel.org/r/20191023153138.23442-1-tony@atomide.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/dma/ti/cppi41.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)
--- a/drivers/dma/ti/cppi41.c +++ b/drivers/dma/ti/cppi41.c @@ -585,9 +585,22 @@ static struct dma_async_tx_descriptor *c 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) { @@ -610,7 +623,13 @@ static struct dma_async_tx_descriptor *c 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)