Re: mc13xxx-core: kernel hangs after 'regmap_read'
From: Mark Brown
Date: Thu May 24 2012 - 08:14:51 EST
On Thu, May 24, 2012 at 09:22:29PM +1000, Marc Reilly wrote:
> > > map->reg_shift = config->pad_bits % 8;
> > > map->format.buf_size = (config->reg_bits
> > >
> > > + config->val_bits
> > >
> > > + map->reg_shift) / 8;
> > Yes, that's been missed in the addition of padding. We should also be
> > using DIV_ROUND_UP() which we aren't at the minute.
> That would break, in _regmap_read_raw():
> ret = map->bus->read(map->bus_context, map->work_buf,
> map->format.reg_bytes + map->format.pad_bytes,
> val, val_len);
> If pad_bytes was 1 here, then the register size would end up being 2 bytes.
The above is about buf_size... pad_bytes isn't in the quoted text which
is the issue.
> The way I understood the pad_bytes field was it was the number of _complete_
> padding bytes (ie, full 8 bits) between the register address and value. Any
> remainder of padding bits is incorporated into the register and shifted by
> shift bits.
Yes.
> > We could also do
> > reg_bytes + pad_bytes + val_bytes which should cover everything I think?
> If we want to cover everything, we could do reg_bytes + pad_bytes + val_bytes
> + 3 ... :) (I'm not seriously suggesting that).
Yes, but the above should be the total that goes onto the wire.
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