Re: [RESEND v4 1/6] misc: Add Synopsys DesignWare xData IP driver

Krzysztof Wilczyński
2021-02-09T17:27:01Z

Hi Gustavo,

[...]
> > The code in question would be (exceprt from the patch):
> >
> > [...]
> > +static int dw_xdata_pcie_probe(struct pci_dev *pdev,
> > + const struct pci_device_id *pid)
> > +{
> > + const struct dw_xdata_pcie_data *pdata = (void *)pid->driver_data;
> > + struct dw_xdata *dw;
> > [...]
> > + dw->rg_region.vaddr = pcim_iomap_table(pdev)[pdata->rg_bar];
> > + if (!dw->rg_region.vaddr)
> > + return -ENOMEM;
> > [...]
> >
> > Perhaps something like the following would would?
> >
> > void __iomem * const *iomap_table;
> >
> > iomap_table = pcim_iomap_table(pdev);
> > if (!iomap_table)
> > return -ENOMEM;
> >
> > dw->rg_region.vaddr = iomap_table[pdata->rg_bar];
> > if (!dw->rg_region.vaddr)
> > return -ENOMEM;
> >
> > With sensible error messages added, of course. What do you think?
>
> I think all the improvements are welcome. I will do that.
> My only doubt is if Bjorn recommends removing the
> iomap_table[pdata->rg_bar] check, after adding the verification on the
> pcim_iomap_table, because all other drivers doesn't do that.

Good point. I only found two drivers that do this extra check:

https://elixir.bootlin.com/linux/v5.11-rc7/source/drivers/crypto/ccp/sp-pci.c#L203
https://elixir.bootlin.com/linux/v5.11-rc7/source/drivers/net/ethernet/amd/xgbe/xgbe-pci.c#L252

Bjorn, do you think that there is some likelihood that the table might
be missing a mapped address for a given BAR?

I don't think that is the case, but should it be the case, then perhaps
adding a small wrapper that would take a BAR and do all the verification
internally might be a good idea.

Krzysztof