Re: mc13xxx-core: kernel hangs after 'regmap_read'

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

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.