Hi Geert-san,
> From: Geert Uytterhoeven, Sent: Tuesday, November 5, 2019 6:53 PM
>
> Hi Shimoda-san,
>
> On Tue, Nov 5, 2019 at 10:26 AM Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> > > From: Geert Uytterhoeven, Sent: Tuesday, November 5, 2019 5:50 PM
> > > On Tue, Nov 5, 2019 at 3:48 AM Yoshihiro Shimoda
> > > <yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> > > > According to the R-Car Gen2/3 manual, "Be sure to write the initial
> > > > value (= H'80FF 0000) to MACCTLR before enabling PCIETCTLR.CFINIT".
> > > > To avoid unexpected behaviors, this patch fixes it. Note that
> > > > the SPCHG bit of MACCTLR register description said "Only writing 1
> > > > is valid and writing 0 is invalid" but this "invalid" means
> > > > "ignored", not "prohibited". So, any documentation conflict doesn't
> > > > exist about writing the MACCTLR register.
> > > >
> > > > Reported-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
> > > > Fixes: c25da4778803 ("PCI: rcar: Add Renesas R-Car PCIe driver")
> > > > Fixes: be20bbcb0a8c ("PCI: rcar: Add the initialization of PCIe link in resume_noirq()")
> > > > Cc: <stable@xxxxxxxxxxxxxxx> # v5.2+
> > > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > >
> > > Thanks for your patch!
> > >
> > > > --- a/drivers/pci/controller/pcie-rcar.c
> > > > +++ b/drivers/pci/controller/pcie-rcar.c
> > > > @@ -91,8 +91,12 @@
> > > > #define LINK_SPEED_2_5GTS (1 << 16)
> > > > #define LINK_SPEED_5_0GTS (2 << 16)
> > > > #define MACCTLR 0x011058
> > > > +#define MACCTLR_RESERVED23_16 GENMASK(23, 16)
> > >
> > > MACCTLR_NFTS_MASK?
> >
> > I should have said on previous email thread [1] though,
> > since SH7786 PCIE HW manual said NFTS (NFTS) but
> > any R-Car SoCs' HW manual said just Reserved with H'FF,
> > so that I prefer to describe RESERVED instead of NFTS.
> > Do you agree?
> >
> > [1]
> > https://marc.info/?l=linux-renesas-soc&m=157242422327368&w=2
>
> My personal stance is to make it as easy as possible for the reader of
> the code ("optimize for reading, not for writing"), as code is written once,
> but read many more times later.
> This is not the first time register bits were documented before, and changed
> to reserved later.
> In this case the resemblance to the SH7786 PCIe block is obvious, and
> the SH7786 hardware user's manual is available publicly.
Thank you for sharing your stance. I understood it. So, I'll fix it as following.
Is it acceptable?
#define MACCTLR_NFTS_MASK GENMASK(23, 16) /* The name is from SH7786 */
Best regards,
Yoshihiro Shimoda
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
