On Thu, Apr 18, 2024 at 12:43:25PM +0300, Andy Shevchenko wrote:
> On Wed, Apr 17, 2024 at 10:54:42PM +0300, Serge Semin wrote:
> > On Tue, Apr 16, 2024 at 09:00:50PM +0300, Andy Shevchenko wrote:
> > > On Tue, Apr 16, 2024 at 07:28:55PM +0300, Serge Semin wrote:
>
> ...
>
> > > > + if (reg_width == DMA_SLAVE_BUSWIDTH_UNDEFINED)
> > > > + reg_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> > > > + else if (!is_power_of_2(reg_width) || reg_width > max_width)
> > > > + return -EINVAL;
> > > > + else /* bus width is valid */
> > > > + return 0;
> > > > +
> > > > + /* Update undefined addr width value */
> > > > + if (dwc->dma_sconfig.direction == DMA_MEM_TO_DEV)
> > > > + dwc->dma_sconfig.dst_addr_width = reg_width;
> > > > + else /* DMA_DEV_TO_MEM */
> > > > + dwc->dma_sconfig.src_addr_width = reg_width;
> > >
> >
> > > So, can't you simply call clamp() for both fields in dwc_config()?
> >
> > Alas I can't. Because the addr-width is the non-memory peripheral
> > setting. We can't change it since the client drivers calculate it on
> > the application-specific basis (CSR widths, transfer length, etc). So
> > we must make sure that the specified value is supported.
>
> What I meant is to convert this "update" part to the clamping, so
> we will have the check as the above like
>
> _verify_()
> {
> if (reg_width == DMA_SLAVE_BUSWIDTH_UNDEFINED)
> return -E...;
> if (!is_power_of_2(reg_width) || reg_width > max_width)
> return -EINVAL;
>
> /* bus width is valid */
> return 0;
> }
>
> dwc_config()
> {
> err = ...
> if (err = ...)
> clamp?
> else if (err)
> return err;
> }
>
> But it's up to you to choose the better variant. I just share the idea.
Ok. Thanks for the suggestion. But I'll stick to my solution then. The
specified *_addr_width values can't/shouldn't be clamped anyway and
having a single verification function will comply to what will be
implemented for the rest of the dwc_onfig() parts in this patchset.
>
> > > > + return 0;
> > > > +}
>
> ...
>
> > > > + int err;
> >
> > > Hmm... we have two functions one of which is using different name for this.
> >
> > Right, the driver uses both variants (see of.c, platform.c, pci.c too).
> >
> > > Can we have a patch to convert to err the other one?
> >
> > To be honest I'd prefer to use the "ret" name instead. It better
> > describes the variable usage context (Although the statements like "if
> > (err) ..." look a bit more readable). So I'd rather convert the "err"
> > vars to "ret". What do you think?
>
> I'm fine with any choice, just my point is to get it consistent across
> the driver.
Ok. "ret" it is then.
-Serge(y)
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
