Messages in this thread | | | Date | Fri, 21 Apr 2023 19:48:38 +0300 | From | Serge Semin <> | Subject | Re: [PATCH v8 5/5] spi: dw: Round of n_bytes to power of 2 |
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On Fri, Apr 21, 2023 at 04:39:30PM +0000, David Laight wrote: > From: Joy Chakraborty > > Sent: 21 April 2023 10:22 > ... > > Sure, I can make the following change in the formatting and send the > > patch series: > > dws->n_bytes = > > roundup_pow_of_two(DIV_ROUND_UP(transfer->bits_per_word, > > BITS_PER_BYTE)); > > Won't checkpatch bleat about that?
Why would it?
> > Is it ever actually valid for the caller to provide a > value that isn't 8, 16 or 32 ?
Judging by this https://elixir.bootlin.com/linux/v6.3-rc7/source/drivers/spi/spi.c#L3630 it is. SPI-controller also supports word lengths within the pre-synthesized range. So it's up to the SPI-peripherals and their protocols what word length to select.
-Serge(y)
> > I'm sure it looked as though some other lengths/counts > where likely to go badly wrong. > > I know there are times when it is useful to bit-bang 'odd' > numbers of bits - like command+address+delay for fast reads > but that is a sub-32bit transfer so (at least somewhere) > is 1 word but not all the bits. > > David > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales)
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