> From: Mark Brown [mailto:[email protected]] > Sent: 03 December 2014 13:03 > > If we can safely handle not having the callback then we should fix the > call site to safely handle a null pointer rather than adding dummy > callbacks. That way this is fixed once for all drivers that need it.
Is it better to test for a null pointer at the spi-bitbang call-site, or get spi-bitbang to add a dummy callback of its own in spi_bitbang_start? The former has the overhead of a test every call, even for those drivers that provide the callback, while the latter has the overhead of a dummy call only for those drivers that don't. At present, spi_bitbang_start assumes that if bitbang->txrx_bufs is defined, then bitbang->setup_transfer is also defined without checking it. > I'd expect to see some code that checks to see if the caller is trying > to change paramters. If you mean in the spi-altera code: The spi-altera driver does not know what the hardware fixed parameters are, so it can't make a decision about whether the caller is trying to change them to something else. If you mean in the spi-bitbang code: The code appears to do this with the do_setup test, but it will always do a setup for the very first transfer in a message regardless, invoking the missing callback. -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
