Hi Andy, On Mon, 2020-06-08 at 16:27 +0300, Andy Shevchenko wrote: > On Sat, Jun 06, 2020 at 02:19:18PM +0800, Dongchun Zhu wrote: > > On Fri, 2020-06-05 at 15:46 +0300, Andy Shevchenko wrote: > > > On Fri, Jun 05, 2020 at 06:54:12PM +0800, Dongchun Zhu wrote: > > ... > > > > > + depends on I2C && VIDEO_V4L2 > > > > > > No compile test? > > > > > > > Sorry? > > Kconfig here is based on the current media tree master branch. > > It is also what the other similar drivers from Dongwoon do. > > COMPILE_TEST. > I dunno if it's established or not practice in media subsystem. > > ... > > > > > +/* > > > > + * DW9768 requires waiting time (delay time) of t_OPR after power-up, > > > > + * or in the case of PD reset taking place. > > > > + */ > > > > +#define DW9768_T_OPR_US 1000 > > > > +#define DW9768_Tvib_MS_BASE10 (64 - 1) > > > > +#define DW9768_AAC_MODE_DEFAULT 2 > > > > > > > +#define DW9768_AAC_TIME_DEFAULT 0x20 > > > > > > Hex? Why not decimal? > > > > > > > There is one optional property 'dongwoon,aac-timing' defined in DT. > > I don't know whether you have noticed that. > > > > 'DW9768_AAC_TIME_DEFAULT' is the value set to AACT[5:0] register. > > I thought the Hex unit should be proper as it is directly written to the > > Hex register. > > I see. I would rather put it like (BIT(6) / 2) to show explicitly that we > choose half of the resolution. > I knew your idea. '(BIT(6) / 2)' may somewhat show the meaning of 'median of the total range of AACT[5:0]'. But this value is still very obscure relative to '0x20'. As I thought that simple is the best, especially for kernel upstream patch. > ... > > > > > + val = ((unsigned char)ret & ~mask) | (val & mask); > > > > > > This cast is weird. > > > > > > > Thanks for the review, but this cast is using classical pattern from > > your suggestion on OV02A10 v5: > > https://patchwork.linuxtv.org/patch/59788/ > > > > So I wonder whether it is still required to be refined currently. > > Or what would it be supposed to do for the cast? > > Okay, does it produce a warning w/o cast? > If yes, replace it at least to be the same type as mask and val. > No. > ... > > > > > + for ( ; val >= 0; val -= DW9768_MOVE_STEPS) { > > > > + ret = dw9768_set_dac(dw9768, val); > > > > + if (ret) { > > > > + dev_err(&client->dev, "I2C write fail: %d", ret); > > > > + return ret; > > > > + } > > > > + usleep_range(move_delay_us, move_delay_us + 1000); > > > > + } > > > > > > > > > It will look more naturally in the multiplier kind of value. > > > > > > unsigned int steps = DIV_ROUND_UP(...); > > > > > > while (steps--) { > > > ...(..., steps * ..._MOVE_STEPS); > > > ... > > > } > > > > > > but double check arithmetics. > > > > The current coding style is actually updated with reference to your > > previous comments on DW9768 v3: > > https://patchwork.linuxtv.org/patch/61856/ > > I understand, but can you consider to go further and see if the proposal works? > In fact, your suggestion is something like one another method to set DAC value to actuator. It is like there may be several solutions to a question. Yes. I just tried the new method and it works as expected. u32 steps = DIV_ROUND_UP(dw9768->focus->val, DW9768_MOVE_STEPS); while (steps--) { ret = dw9768_set_dac(dw9768, steps * DW9768_MOVE_STEPS); if (ret) return ret; usleep_range(move_delay_us, move_delay_us + 1000); } But from my perspective, I may prefer to the original method. As here what we really care is the DAC value, 'dw9768_set_dac(dw9768, val)' seems more simple.
