On Sun, 30 Dec 2018, I wrote:
> On Sat, 29 Dec 2018, LEROY Christophe wrote:
>
> > Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> a ?crit?:
> >
> > > Make use of arch_nvram_ops in device drivers so that the nvram_* function
> > > exports can be removed.
> > >
> > > Since they are no longer global symbols, rename the PPC32 nvram_* functions
> > > appropriately.
> > >
> > > Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
> > > ---
> > > arch/powerpc/kernel/setup_32.c | 8 ++++----
> > > drivers/char/generic_nvram.c | 4 ++--
> > > drivers/video/fbdev/controlfb.c | 4 ++--
> > > drivers/video/fbdev/imsttfb.c | 4 ++--
> > > drivers/video/fbdev/matrox/matroxfb_base.c | 2 +-
> > > drivers/video/fbdev/platinumfb.c | 4 ++--
> > > drivers/video/fbdev/valkyriefb.c | 4 ++--
> > > 7 files changed, 15 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
> > > index e0d045677472..bdbe6acbef11 100644
> > > --- a/arch/powerpc/kernel/setup_32.c
> > > +++ b/arch/powerpc/kernel/setup_32.c
> > > @@ -152,20 +152,18 @@ __setup("l3cr=", ppc_setup_l3cr);
> > >
> > > #ifdef CONFIG_GENERIC_NVRAM
> > >
> > > -unsigned char nvram_read_byte(int addr)
> > > +static unsigned char ppc_nvram_read_byte(int addr)
> > > {
> > > if (ppc_md.nvram_read_val)
> > > return ppc_md.nvram_read_val(addr);
> > > return 0xff;
> > > }
> > > -EXPORT_SYMBOL(nvram_read_byte);
> > >
> > > -void nvram_write_byte(unsigned char val, int addr)
> > > +static void ppc_nvram_write_byte(unsigned char val, int addr)
> > > {
> > > if (ppc_md.nvram_write_val)
> > > ppc_md.nvram_write_val(addr, val);
> > > }
> > > -EXPORT_SYMBOL(nvram_write_byte);
> > >
> > > static ssize_t ppc_nvram_get_size(void)
> > > {
> > > @@ -182,6 +180,8 @@ static long ppc_nvram_sync(void)
> > > }
> > >
> > > const struct nvram_ops arch_nvram_ops = {
> > > + .read_byte = ppc_nvram_read_byte,
> > > + .write_byte = ppc_nvram_write_byte,
> > > .get_size = ppc_nvram_get_size,
> > > .sync = ppc_nvram_sync,
> > > };
> > > diff --git a/drivers/char/generic_nvram.c b/drivers/char/generic_nvram.c
> > > index f32d5663de95..41b76bf9614e 100644
> > > --- a/drivers/char/generic_nvram.c
> > > +++ b/drivers/char/generic_nvram.c
> > > @@ -48,7 +48,7 @@ static ssize_t read_nvram(struct file *file, char __user
> > > *buf,
> > > if (*ppos >= nvram_len)
> > > return 0;
> > > for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
> > > - if (__put_user(nvram_read_byte(i), p))
> > > + if (__put_user(arch_nvram_ops.read_byte(i), p))
> >
> > Instead of modifying all drivers (in this patch and previous ones related to
> > other arches), wouldn't it be better to add helpers like the following in
> > nvram.h:
> >
> > Static inline unsigned char nvram_read_byte(int addr)
> > {
> > return arch_nvram_ops.read_byte(addr);
> > }
> >
>
> Is there some benefit, or is that just personal taste?
>
> Avoiding changes to call sites avoids code review, but I think 1) the
> thinkpad_acpi changes have already been reviewed and 2) the fbdev changes
> need review anyway.
>
> Your suggesion would add several new entities and one extra layer of
> indirection.
>
Contrary to what I said above, this kind of double indirection could be
useful if it allows us to avoid the kind of double indirection which Arnd
objected to (which arises when an arch_nvram_ops method invokes a ppc_md
method). For example,
static inline unsigned char nvram_read_byte(int addr)
{
#ifdef CONFIG_PPC
return ppc_md.nvram_read_byte(addr);
#else
return arch_nvram_ops.read_byte(addr);
#endif
}
I'll try this approach for v9 if there are no objections. It may be the
least invasive approach. Also, arch_nvram_ops can remain const.
--
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