Ops, sorry, I have to resend the e-mail since I used a mail
address which is not subscribed to the lkml.
Andi
On Sun, Feb 17, 2013 at 03:17:57PM +0100, Andi Shyti wrote:
> > >> + char name[30];
> > >> + char buf[50];
> > >> +
> > >> + if (size >= sizeof(buf))
> > >> + size = sizeof(buf);
> > >
> > > what's the point of this?
> >
> > This is a way to limit copied from userspace data by available buffer size,
> > widely used in current kernel sources. Are you implying there is some
> > better (more graceful) way?
>
> No indeed :)
> There is no other way, sorry for polluting the review :)
>
> > >> + if ((pins[2] & 1) || (pins[3] & 1)) {
> > >> + lanes |= (1 << 1);
> > >> + ret |= tc358765_write_register(dssdev, PPI_D0S_CLRSIPOCOUNT,
> > >> + board_data->clrsipo);
> > >> + }
> > >> + if ((pins[4] & 1) || (pins[5] & 1)) {
> > >> + lanes |= (1 << 2);
> > >> + ret |= tc358765_write_register(dssdev, PPI_D1S_CLRSIPOCOUNT,
> > >> + board_data->clrsipo);
> > >> + }
> > >> + if ((pins[6] & 1) || (pins[7] & 1)) {
> > >> + lanes |= (1 << 3);
> > >> + ret |= tc358765_write_register(dssdev, PPI_D2S_CLRSIPOCOUNT,
> > >> + board_data->clrsipo);
> > >> + }
> > >> + if ((pins[8] & 1) || (pins[9] & 1)) {
> > >> + lanes |= (1 << 4);
> > >> + ret |= tc358765_write_register(dssdev, PPI_D3S_CLRSIPOCOUNT,
> > >> + board_data->clrsipo);
> > >> + }
> > >
> > > Can't this be done in one single multiwrighting command since
> > > this registers are consecutive?
> > >
> > > You build once the array to write and you send it at once.
> >
> > In this particular case I disagree. Yes, it will be a little bit
> > faster, however:
> > 1) we write this for panel initialization only (so no impact in other cases)
> > 2) multiwriting of array will make code reading more difficult
> >
> > So I would like to leave it as-is
> > Same is for next your similar comment.
>
> If the hw is providing us some ways for simplifying the code I
> would use it. In this case we are talking about the i2c feature
> of multiwriting and multireading.
>
> Let's assume that we want to write on 8 different consecutive
> registers. In my opinion this aproach is quite "heavy":
>
> uX register;
>
> register = value1;
> i2c_write(REG1, register);
>
> register = value2;
> i2c_write(REG2, register);
>
> ...
>
> Usually what I do is this:
>
> uX register[8];
>
> for (i = 0; i < 8; i++)
> register |= valuei << i; (or register[i] = valuei or whatever)
>
> i2c_multi_write(REG, register, 8);
>
> of course this is a simplified example in pseudocode. I think
> it's more readable and we are making a better use of the i2c
> protocol.
>
> In your case you have some if statement that are making the multi
> writing more difficult, but still is not impossible.
>
> At the end it's still a matter of taste, so that you are free to
> choose whatever you prefer :)
>
> Andi
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