Hi Dmitry, On 13/11/2019 01:23, Dmitry Torokhov wrote:
Do we really need to re-fetch model (and firmware ID) on each access? Can we query it as probe time and cache? This I think would simplify the driver, as you probably would not need to hook it into the ISR. Can you just post a read/write transaction to fetch it without waiting for interrupt? Or, if single transaction does not work and you need to wait for certain time for response - just add msleep() and maybe mark driver for async probe...
Having the sysfs access actually read the data from the device can be useful to check that the I2C link is still working (in a test scenario).
The documentation does say that one should wait for an interrupt after issuing the commands.
The msleep() could work but the value would have to be empirical and could be fragile.
Furthermore what happens if a touch event occurs just after sending the query request?
Having the interrupt handler be the single read() point and dispatching solves that problem, even if it does complicate the driver to some extent.
One further thing is that there are other commands that may be added in the future that cannot be cached (commands to do tests or fimware updates for example).
Regards, Martin
