On Thu, Nov 13, 2014 at 2:13 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Thursday 13 November 2014 12:58:08 Andrew Bresticker wrote:
>> +
>> +static bool mdc_filter_fn(struct dma_chan *chan, void *fn_param)
>> +{
>> + struct mdc_filter_data *data = fn_param;
>> + struct mdc_chan *mchan;
>> +
>> + if (chan->device->dev->driver == &mdc_dma_driver.driver) {
>> + mchan = to_mdc_chan(chan);
>> + if (!(data->mask & BIT(mchan->chan_nr)))
>> + return false;
>> + mchan->periph = data->periph;
>> + mchan->thread = data->thread;
>> + return true;
>> + }
>> + return false;
>> +}
>> +
>> +static struct dma_chan *mdc_of_xlate(struct of_phandle_args *dma_spec,
>> + struct of_dma *ofdma)
>> +{
>> + struct mdc_dma *mdma = ofdma->of_dma_data;
>> + struct mdc_filter_data data;
>> +
>> + if (dma_spec->args_count != 3)
>> + return NULL;
>> +
>> + data.periph = dma_spec->args[0];
>> + data.mask = dma_spec->args[1];
>> + data.thread = dma_spec->args[2];
>> +
>> + return dma_request_channel(mdma->dma_dev.cap_mask, mdc_filter_fn,
>> + &data);
>> +}
>
> The filter function is broken if you ever have multiple instances
> of the device. Better avoid calling dma_request_channel and scan
> the channels that the device knows about.
It seems unlikely that there would be multiple instances of this IP in
a system, but it doesn't hurt to be safe. Perhaps instead of
iterating through the list here I could extend struct mdc_filter_data
to include a pointer to the struct dma_device corresponding to this
instance of the MDC and compare based on that.
>> +
>> +#define PISTACHIO_CR_PERIPH_DMA_ROUTE(ch) (0x120 + 0x4 * ((ch) / 4))
>> +#define PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(ch) (8 * ((ch) % 4))
>> +#define PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK 0x3f
>> +
>> +static void pistachio_mdc_enable_chan(struct mdc_chan *mchan)
>> +{
>> + struct mdc_dma *mdma = mchan->mdma;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&mdma->lock, flags);
>> + regmap_update_bits(mdma->periph_regs,
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE(mchan->chan_nr),
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK <<
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr),
>> + mchan->periph <<
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr));
>> + spin_unlock_irqrestore(&mdma->lock, flags);
>> +}
>> +
>> +static void pistachio_mdc_disable_chan(struct mdc_chan *mchan)
>> +{
>> + struct mdc_dma *mdma = mchan->mdma;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&mdma->lock, flags);
>> + regmap_update_bits(mdma->periph_regs,
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE(mchan->chan_nr),
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE_MASK <<
>> + PISTACHIO_CR_PERIPH_DMA_ROUTE_SHIFT(mchan->chan_nr),
>> + 0);
>> + spin_unlock_irqrestore(&mdma->lock, flags);
>> +}
>
> Regmap has its own locking, no need to add another level.
Ah, right. I'll drop the locking.
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