Hi,
On Fri, Apr 26, 2024 at 3:09 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
>
> > 2. Accept that a slightly less efficient handling of the error case
> > and perhaps a less intuitive API, but avoid the goto.
> >
> > Essentially you could pass in "ret" and have the function be a no-op
> > if an error is already present. Something like this:
> >
> > void mipi_dsi_dcs_write_buffer_multi(struct mipi_dsi_device *dsi,
> > const void *data, size_t len, int *accum_ret)
> > {
> > if (*accum_ret)
> > return;
> >
> > *accum_ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
>
> No reason you couldn't do error logging here
>
> if (*accum_ret)
> dev_err(...)
Yup, exactly. This is probably best.
> > }
> >
> > ...and then the caller:
> >
> > int ret;
> >
> > ret = 0;
> > mipi_dsi_dcs_write_seq_multi(dsi, HX83102_SETSPCCMD, 0xcd, &ret);
> > mipi_dsi_dcs_write_seq_multi(dsi, HX83102_SETMIPI, 0x84, &ret);
> > mipi_dsi_dcs_write_seq_multi(dsi, HX83102_SETSPCCMD, 0x3f, &ret);
> > mipi_dsi_dcs_write_seq_multi(dsi, HX83102_SETVDC, 0x1b, 0x04, &ret);
> > if (ret)
> > goto some_cmd_failed;
> >
> > This has similar properties to solution #1.
>
> I like this option the best, for the simple reason that the caller side
> is aware of what's going on, there's no magic control flow happening,
> and they can add error handling in the middle if they so choose.
Sounds good to me. I went back and forth a bit between solution #1 and
this and I see the benefits of both. If folks like this one I think we
should run with it. Certainly it's better than the current hidden
return.
> I don't find this unintuitive, but if it helps, you could conceivably
> add a context parameter:
>
> struct mipi_dsi_seq_context context = {
> .dsi = dsi,
> };
>
> mipi_dsi_dcs_write_seq(&context, HX83102_SETSPCCMD, 0xcd);
> ...
>
> if (context.ret)
> ...
>
> And even have further control in the context whether to log or keep
> going or whatever.
I agree there are some benefits of adding the extra "context"
abstraction and we can go that way if you want, but I lean towards the
simplicity of just passing in the accumulated return value like I did
in my example.
I'll try to write up patches and see if I can post them later today.
-Doug
