From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Dan Carpenter <dan.carpenter@oracle.com>,
Matthias Fuchs <matthias.fuchs@esd-electronics.com>
Cc: Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] powerpc/44x: mask and shift to zero bug
Date: Sun, 27 Aug 2017 14:56:31 +1000 [thread overview]
Message-ID: <1503809791.3814.43.camel@kernel.crashing.org> (raw)
In-Reply-To: <20170825103340.op3uphrv3eyeutiz@mwanda>
On Fri, 2017-08-25 at 13:33 +0300, Dan Carpenter wrote:
> My static checker complains that 0x00001800 >> 13 is zero. Looking at
> the context, it seems like a copy and paste bug from the line below and
> probably 0x3 << 13 or 0x00006000 was intended.
>
> Fixes: 2af59f7d5c3e ("[POWERPC] 4xx: Add 405GPr and 405EP support in boot wrapper")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Not tested!
>
> diff --git a/arch/powerpc/boot/4xx.c b/arch/powerpc/boot/4xx.c
> index 9d3bd4c45a24..f7da65169124 100644
> --- a/arch/powerpc/boot/4xx.c
> +++ b/arch/powerpc/boot/4xx.c
> @@ -564,7 +564,7 @@ void ibm405gp_fixup_clocks(unsigned int sys_clk, unsigned int ser_clk)
> fbdv = 16;
> cbdv = ((pllmr & 0x00060000) >> 17) + 1; /* CPU:PLB */
> opdv = ((pllmr & 0x00018000) >> 15) + 1; /* PLB:OPB */
> - ppdv = ((pllmr & 0x00001800) >> 13) + 1; /* PLB:PCI */
> + ppdv = ((pllmr & 0x00006000) >> 13) + 1; /* PLB:PCI */
> epdv = ((pllmr & 0x00001800) >> 11) + 2; /* PLB:EBC */
> udiv = ((cpc0_cr0 & 0x3e) >> 1) + 1;
That rings a bell... Is this something we tried to fix before and had
problems ? The thing is when I opened the 405GP and EP manual PDF,
evince had memorized that this register was the last page I looked at
:-) And I don't remember how many years ago that is.
According to the 405gp spec ppdv is IBM bits 17,18 so your patch is
correct.
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
next prev parent reply other threads:[~2017-08-27 4:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-25 10:33 [PATCH] powerpc/44x: mask and shift to zero bug Dan Carpenter
2017-08-27 4:56 ` Benjamin Herrenschmidt [this message]
2017-08-28 7:57 ` Dan Carpenter
2017-08-28 8:36 ` Dan Carpenter
2017-08-28 11:19 ` Michael Ellerman
2017-08-31 11:36 ` Michael Ellerman
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