On Thu, Oct 22, 2015 at 08:09:38PM +0100, Damien Horsley wrote:
> On 19/10/15 18:47, Mark Brown wrote:
> > On Mon, Oct 12, 2015 at 01:40:29PM +0100, Damien Horsley wrote:
> > The APIs here all seem a bit odd - for example the enable API taking a
> > register value as an argument (normally reg is a register address BTW)
> > and returning a value but the disable API doing a read/modify/write
> > cycle.
> Sure. It reduces the number of register accesses this way, but the
> difference in execution time is not significant. Would you prefer these
> to both do read-modify-writes?
I would prefer that the functions look consistent with each other and
ideally resemble common register acceess idioms in the kernel.
> >> +static inline void img_i2s_in_flush(struct img_i2s_in *i2s)
> >> +{
> >> + int i;
> >> + u32 reg;
> >> +
> >> + for (i = 0; i < i2s->active_channels; i++) {
> >> + reg = img_i2s_in_ch_disable(i2s, i);
> >> + reg |= IMG_I2S_IN_CH_CTL_FIFO_FLUSH_MASK;
> >> + img_i2s_in_ch_writel(i2s, i, reg, IMG_I2S_IN_CH_CTL);
> >> + reg &= ~IMG_I2S_IN_CH_CTL_FIFO_FLUSH_MASK;
> >> + img_i2s_in_ch_writel(i2s, i, reg, IMG_I2S_IN_CH_CTL);
> >> + img_i2s_in_ch_enable(i2s, i, reg);
> >> + }
> >> +}
> > This all seems to be connected to this, which is itself slightly funky
> > especially in the context of the only user...
> They are also used during hw_params and set_format.
My point is that the flush function has only one user.
> >> + case SNDRV_PCM_TRIGGER_STOP:
> >> + case SNDRV_PCM_TRIGGER_SUSPEND:
> >> + case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> >> + reg = img_i2s_in_readl(i2s, IMG_I2S_IN_CTL);
> >> + reg &= ~IMG_I2S_IN_CTL_ME_MASK;
> >> + img_i2s_in_writel(i2s, reg, IMG_I2S_IN_CTL);
> >> + img_i2s_in_flush(i2s);
> >> + break;
> > ...which looks like it'll enable everything, then disable and reenable.
> > Plus needing to do a flush on trigger seems weird.
> If the FIFOs are not flushed, some samples from the previous stream will
> be transferred to the user application when the block is started again
Shouldn't we be doing that flush on stream close instead? If nothing
else the flush is going to discard a bit of data if the stream is just
paused.
> >> + if ((channels < 2) ||
> >> + (channels > (i2s->max_i2s_chan * 2)) ||
> >> + (channels % 2))
> >> + return -EINVAL;
> > This indentation is very weird.
> Ok. What is the correct indentation for this?
Align the continuation lines of the if condition with the first line.
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