Hi Wolfram, On 28 August 2017 at 23:13, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: > >> >> + /* >> >> + * If we did not get one ACK from slave when writing data, we should >> >> + * dump all registers to check I2C status. >> > >> > Why? I would say no. NACK from a slave can always happen, e.g. when an >> > EEPROM is busy erasing a page. >> >> For our I2C controller databook, if the master did not get one ACK >> from slave when writing data to salve, we should send one STOP signal >> to abort this data transfer or generate one repeated START signal to >> start one new data transfer cycle. Considering our I2C usage > > Yes, so far so good. > >> scenarios, we should dump registers to analyze I2C status and notify >> to user to re-start new data transfer. > > I disagree here. You notify the users by returning -EIO. The upper layer > (e.g. the i2c client driver) will handle it, like the EEPROM driver > might retry after a while. This all is expected behaviour, so no need to > print the registers to the logfile. > > If you really, really want to keep it, make it debug output. But I think > the sentence "we should dump all registers" needs to be rephrased. Make sense. I will remove the registers printing here. > >> As I explained before, in our Spreadtrum platform, our regulator >> driver will depend on I2C driver and the regulator driver uses >> subsys_initcall() level to initialize. Moreover some other drivers >> like GPU, they will depend on regulator to set voltage and they also >> need initialization much earlier. >> >> Since it is arch_initcall() level, Andy suggested I should get rid of >> tristate (use bool) and drop module.h here and all leftovers like >> MODULE_*() calls including module_exit(). > > I see. So the driver is really so essential for proper bootup that it is > not even allowed to be unloaded. I might make an exception here and Yes. > allow arch_initcall() then. But I do wonder: did you try deferred > probing all over the place? Many modules (like GPU) need set voltage earlier by regulator which depends on I2C ( or we also need regulate voltage for big-cores ASAP), if we defer to set voltage for GPU or other modules, maybe will cause some system problems. Thanks for your comments. -- Baolin.wang Best Regards -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
