Re: [PATCH v2 10/14] mmc: jz4740: Use dma_request_chan()

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Le jeu. 15 mars 2018 à 18:12, Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxx> a écrit :
On Thu, 2018-03-15 at 17:59 -0300, Paul Cercueil wrote:
 Hi,

 Le lun. 12 mars 2018 à 18:55, Ezequiel Garcia
 <ezequiel@xxxxxxxxxxxxxxxxxxxx> a écrit :
 > From: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxx>
 >
 > Replace dma_request_channel() with dma_request_chan(),
 > which also supports probing from the devicetree.
 >
 > Tested-by: Mathieu Malaterre <malat@xxxxxxxxxx>
 > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxx>
 > ---
 >  drivers/mmc/host/jz4740_mmc.c | 22 +++++++---------------
 >  1 file changed, 7 insertions(+), 15 deletions(-)
 >
 > diff --git a/drivers/mmc/host/jz4740_mmc.c
 > b/drivers/mmc/host/jz4740_mmc.c
 > index c3ec8e662706..37183fe32ef8 100644
 > --- a/drivers/mmc/host/jz4740_mmc.c
 > +++ b/drivers/mmc/host/jz4740_mmc.c
 > @@ -225,31 +225,23 @@ static void
 > jz4740_mmc_release_dma_channels(struct jz4740_mmc_host *host)
 >
 >  static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host
 > *host)
 >  {
 > -	dma_cap_mask_t mask;
 > -
 > -	dma_cap_zero(mask);
 > -	dma_cap_set(DMA_SLAVE, mask);
 > -
 > -	host->dma_tx = dma_request_channel(mask, NULL, host);
 > -	if (!host->dma_tx) {
 > +	host->dma_tx = dma_request_chan(mmc_dev(host->mmc), "tx");
 > +	if (IS_ERR(host->dma_tx)) {
 >  		dev_err(mmc_dev(host->mmc), "Failed to get dma_tx
 > channel\n");
 > -		return -ENODEV;
 > +		return PTR_ERR(host->dma_tx);
 >  	}
 >
 > -	host->dma_rx = dma_request_channel(mask, NULL, host);
 > -	if (!host->dma_rx) {
 > +	host->dma_rx = dma_request_chan(mmc_dev(host->mmc), "rx");

 I suspect this breaks on jz4740... Did you test?


No, but code inspecting I was expecting it wouldn't break anything.
dma_request_channel() searches for a slave channel, via the DMA_SLAVE
mask that the driver sets.

dma_request_chan() seems to fallback to do the same.

Alright, I overlooked that. I guess it's fine then.

struct dma_chan *dma_request_chan(struct device *dev, const char *name)
{
        struct dma_device *d, *_d;
        struct dma_chan *chan = NULL;

        /* If device-tree is present get slave info from here */
        if (dev->of_node)
                chan = of_dma_request_slave_channel(dev->of_node,
name);

        /* ... */

        if (chan) {
/* Valid channel found or requester need to be deferred
*/
                if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
                        return chan;
        }

        /* Try to find the channel via the DMA filter map(s) */
        mutex_lock(&dma_list_mutex);
        list_for_each_entry_safe(d, _d, &dma_device_list, global_node)
{
                dma_cap_mask_t mask;
                const struct dma_slave_map *map = dma_filter_match(d,
name, dev);

                if (!map)
                        continue;

                dma_cap_zero(mask);
                dma_cap_set(DMA_SLAVE, mask);

                chan = find_candidate(d, &mask, d->filter.fn, map-
param);
                if (!IS_ERR(chan))
                        break;
        }
        mutex_unlock(&dma_list_mutex);

        return chan ? chan : ERR_PTR(-EPROBE_DEFER);
}

Unfortunately, I don't have anything but a jz4780 Ci20, so can't really
test this.

Apart from this patch, your patchset looks sufficiently similar to what I successfully tested on jz4740, so it's safe to assume it doesn't break anything. Unfortunately I won't be able to test it on jz4740 before the end of this year.

Thanks,
Eze

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