Messages in this thread | | | Date | Tue, 15 Feb 2011 22:12:54 +1300 | From | Ryan Mallon <> | Subject | Re: [PATCH v9] spi: New driver for Altera SPI |
| |
On 15/02/11 20:04, Thomas Chou wrote: > Dear Ryan, > > On 02/14/2011 10:20 AM, Ryan Mallon wrote: >> On 02/14/2011 03:10 PM, Thomas Chou wrote: >>> This patch adds a new SPI driver to support the Altera SOPC Builder >>> SPI component. It uses the bitbanging library. >>> >>> Signed-off-by: Thomas Chou<thomas@wytron.com.tw> >>> --- >> >>> +struct altera_spi { >>> + /* bitbang has to be first */ >>> + struct spi_bitbang bitbang; >> >> Is this still true? I had a quick look and can't see anything which >> relies on spi_bitbang being the first entry. Things like this should be >> using container_of so that position in the struct is irrelevant. >> >> ~Ryan >> > > Yes, sadly true. This is due to the implementation of the bitbanging > library, spi_bitbang.c, which assumes the struct spi_bitbang is the > first of drvdata. Though it could be changed in the future (beyond this > little driver), every bitbanging library user has to follow this for now.
Hmm, I see how it works now. Shouldn't the conversion be done like this:
struct spi_bitbang *bitbang = spi_master_get_devdata(master); struct altera_spi *altera = container_of(bitbang, struct altera_spi, bitbang);
Which doesn't require the bitbang field to be the first in the struct and makes it more clear what is actually going on. The above could be wrapped into a to_altera_spi macro.
~Ryan
| |