Re: [PATCH] mfd: ls2kbmc: Fix iomem pointer handling in video mode parsing

[Binbin Zhou]

On Fri, Jun 19, 2026 at 3:12 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
>
> Hi, Binbin,
>
> On Tue, Jun 16, 2026 at 7:56 PM Binbin Zhou <zhoubinbin@xxxxxxxxxxx> wrote:
> >
> > Use pointers annotated with the __iomem marker for all iomem map calls,
> > and creates a local copy of the mapped IO memory for future access in
> > the code. memcpy_fromio() and memcpy_toio() are used to read/write data
> > from/to mapped IO memory
> >
> > Fixes: 0d64f6d1ffe9 ("mfd: ls2kbmc: Introduce Loongson-2K BMC core driver")
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202603021730.Yy3QXYTw-lkp@xxxxxxxxx/
> > Closes: https://lore.kernel.org/oe-kbuild-all/202606120639.WG6eb8VU-lkp@xxxxxxxxx/
> > Signed-off-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
> > ---
> >  drivers/mfd/ls2k-bmc-core.c | 13 ++++++++++---
> >  1 file changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
> > index 408056bfb2fe..c40b1a7c4ea4 100644
> > --- a/drivers/mfd/ls2k-bmc-core.c
> > +++ b/drivers/mfd/ls2k-bmc-core.c
> > @@ -427,14 +427,21 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
> >   */
> >  static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
> >  {
> > -       char *mode;
> > +       void *buf __free(kfree) = NULL;
> > +       void __iomem *base;
> >         int depth, ret;
> > +       char *mode;
> >
> >         /* The last 16M of PCI BAR0 is used to store the resolution string. */
> > -       mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
> > -       if (!mode)
> > +       base = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
> > +       if (!base)
> > +               return -ENOMEM;
> > +
> > +       buf = kmalloc(SZ_16M, GFP_KERNEL);
> > +       if (!buf)
> >                 return -ENOMEM;
> >
> > +       mode = (char *)buf;
> I think you miss "memcpy_fromio(buf, base, SZ_16M)" here.

Yes, it was missed and will be added in the next version.
Also, `buf` and `mode` can be combined into a single variable.

` char *mode __free(kfree) = NULL;`
>
> Huacai
>
> >         /* The resolution field starts with the flag "video=". */
> >         if (!strncmp(mode, "video=", 6))
> >                 mode = mode + 6;
> >
> > base-commit: b07f7904e0523170856876e4412be852377d492a
> > --
> > 2.52.0
> >

--
Thanks.
Binbin