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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Simon Horman <horms@verge.net.au>,
	linux-pci <linux-pci@vger.kernel.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	stable <stable@vger.kernel.org>,
	Marek Vasut <marek.vasut+renesas@gmail.com>
Subject: Re: [PATCH v2] PCI: rcar: Fix writing the MACCTLR register value
Date: Wed, 9 Oct 2019 10:58:23 +0200	[thread overview]
Message-ID: <CAMuHMdV5N=JrVi3EwfFV4wgXo-xDQL0ptaqmauvzzQbDfWq+CQ@mail.gmail.com> (raw)
In-Reply-To: <1570593791-6958-1-git-send-email-yoshihiro.shimoda.uh@renesas.com>

Hi Shimoda-san,

On Wed, Oct 9, 2019 at 6:03 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> According to the R-Car Gen2/3 manual, the bit 0 of MACCTLR register
> should be written to 0 because the register is set to 1 on reset.
> To avoid unexpected behaviors from this incorrect setting, this
> patch fixes it.
>
> Fixes: b3327f7fae66 ("PCI: rcar: Try increasing PCIe link speed to 5 GT/s at boot")
> Cc: <stable@vger.kernel.org> # v4.9+
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

Thanks for your patch!

This patch fixes the issue where the register is written, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

However, according to the R-Car H1, Gen2, and Gen3 Hardware User's
Manuals, this reserved bit should be cleared on initialization.
Are we sure that is guaranteed to happen? If the checks at the top of
rcar_pcie_force_speedup() trigger, the register is never written to,
and the bit may still be set?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

  parent reply	other threads:[~2019-10-09  8:58 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09  4:03 [PATCH v2] PCI: rcar: Fix writing the MACCTLR register value Yoshihiro Shimoda
2019-10-09  8:48 ` Sergei Shtylyov
2019-10-09  8:54   ` Yoshihiro Shimoda
2019-10-09  8:58     ` Sergei Shtylyov
2019-10-09  9:45       ` Yoshihiro Shimoda
2019-10-09  8:58 ` Geert Uytterhoeven [this message]
2019-10-09  9:57   ` Yoshihiro Shimoda

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