Messages in this thread | | | Date | Mon, 15 Oct 2007 13:33:31 -0400 | From | "Dmitry Torokhov" <> | Subject | Re: [PATCH 2/3] Input/Touchscreen Driver: add support AD7877 touchscreen driver |
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Hi Michael,
On 10/15/07, Hennerich, Michael <Michael.Hennerich@analog.com> 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.
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