Re: [PATCH v3 3/3] counter: 104-quad-8: Utilize helper functions to handle PR, FLAG and PSC

William Breathitt Gray
2023-04-11T14:05:38Z

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On Tue, Apr 11, 2023 at 04:50:03PM +0300, Andy Shevchenko wrote:
> On Mon, Apr 10, 2023 at 10:03:13AM -0400, William Breathitt Gray wrote:
> > The Preset Register (PR), Flag Register (FLAG), and Filter Clock
> > Prescaler (PSC) have common usage patterns. Wrap up such usage into
> > dedicated functions to improve code clarity.
>
> ...
>
> > *val = 0;
>
> Is not needed now as always being initialized by below call.

The regmap_noinc_read() call only reads the number of bytes requested.
Since we request 3 bytes, the upper bytes of the u64 val remain
uninitialized, so that is why we need to set *val = 0. This isn't
immediately clear in the code, so I can add a comment to make it
explicit.

>
> > spin_lock_irqsave(&priv->lock, irqflags);
> >
> > iowrite8(SELECT_RLD | RESET_BP | TRANSFER_CNTR_TO_OL, &chan->control);
> > -
> > - for (i = 0; i < 3; i++)
> > - *val |= (unsigned long)ioread8(&chan->data) << (8 * i);
> > + ioread8_rep(&chan->data, val, 3);
> >
> > spin_unlock_irqrestore(&priv->lock, irqflags);
>
> ...
>
> > + struct channel_reg __iomem *const chan = priv->reg->channel + id;
>
> Not sure if array representation will look better here and elsewhere.
>
> struct channel_reg __iomem *const chan = &priv->reg->channel[id];

Perhaps so, but all these struct channel_reg lines will go away in the
next patch [0] migrating to the regmap API, so for the sake of stability
of this patch I hesitate to change these lines.

William Breathitt Gray

[0] https://lore.kernel.org/all/20230410141252.143998-1-william.gray@linaro.org/

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