Hi Michael, On 10/15/07, Hennerich, Michael <Michael.Hennerich@xxxxxxxxxx> wrote: > > > >> + > >> +static int ad7877_read(struct device *dev, u16 reg) > >> +{ > >> + struct spi_device *spi = to_spi_device(dev); > >> + struct ser_req *req = kzalloc(sizeof *req, > GFP_KERNEL); > > > >How many reads can happen at once? Maybe allocate 1 ser_req per > >touchcsreen when creating it? > > ad7877_read_adc, ad7877_read and ad7877_write are just used by the sysfs > hooks. Touchscreen samples are read by the kthread using a different > message struct. So far each sysfs invocation got its own storage for the > spi message, which then is handed over to the SPI bus driver. > The SPI bus driver serializes transfers in a kthread. > > Two different processes could access the drivers sysfs hooks. > > Using one ser_req per touch screen could require additional locking? > Things at is, looks pretty safe to me. > OK, fair enough. -- Dmitry - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html