Re:Re: [PATCH v3] powerpc/fsl-85xx: fix compile error

[王文虎]

From: Michael Ellerman <mpe at ellerman.id.au>
 Date: 2020-03-17 19:22:13
To:"王文虎" <wenhu.wang at vivo.com>
 cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>,Paul Mackerras <paulus at samba.org>,Allison Randal <allison at lohutok.net>,Richard Fontana <rfontana at redhat.com>,Greg Kroah-Hartman <gregkh at linuxfoundation.org>,Thomas Gleixner <tglx at linutronix.de>,linuxppc-dev at lists.ozlabs.org,linux-kernel at vger.kernel.org,trivial at kernel.org,kernel at vivo.com,stable <stable at vger.kernel.org>
Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>王文虎 <wenhu.wang at vivo.com> writes:
>> From: Michael Ellerman <mpe at ellerman.id.au>
>>  Date: 2020-03-16 17:41:12
>> To:WANG Wenhu <wenhu.wang at vivo.com>,Benjamin Herrenschmidt <benh at kernel.crashing.org>,Paul Mackerras <paulus at samba.org>,WANG Wenhu <wenhu.wang at vivo.com>,Allison Randal <allison at lohutok.net>,Richard Fontana <rfontana at redhat.com>,Greg Kroah-Hartman <gregkh at linuxfoundation.org>,Thomas Gleixner <tglx at linutronix.de>,linuxppc-dev at lists.ozlabs.org,linux-kernel at vger.kernel.org
>>  cc: trivial at kernel.org,kernel at vivo.com,stable <stable at vger.kernel.org>
>> Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>WANG Wenhu <wenhu.wang at vivo.com> writes:
>>>> Include "linux/of_address.h" to fix the compile error for
>>>> mpc85xx_l2ctlr_of_probe() when compiling fsl_85xx_cache_sram.c.
>>>>
>>>>   CC      arch/powerpc/sysdev/fsl_85xx_l2ctlr.o
>>>> arch/powerpc/sysdev/fsl_85xx_l2ctlr.c: In function ‘mpc85xx_l2ctlr_of_probe’:
>>>> arch/powerpc/sysdev/fsl_85xx_l2ctlr.c:90:11: error: implicit declaration of function ‘of_iomap’; did you mean ‘pci_iomap’? [-Werror=implicit-function-declaration]
>>>>   l2ctlr = of_iomap(dev->dev.of_node, 0);
>>>>            ^~~~~~~~
>>>>            pci_iomap
>>>> arch/powerpc/sysdev/fsl_85xx_l2ctlr.c:90:9: error: assignment makes pointer from integer without a cast [-Werror=int-conversion]
>>>>   l2ctlr = of_iomap(dev->dev.of_node, 0);
>>>>          ^
>>>> cc1: all warnings being treated as errors
>>>> scripts/Makefile.build:267: recipe for target 'arch/powerpc/sysdev/fsl_85xx_l2ctlr.o' failed
>>>> make[2]: *** [arch/powerpc/sysdev/fsl_85xx_l2ctlr.o] Error 1
>>>>
>>>> Fixes: commit 6db92cc9d07d ("powerpc/85xx: add cache-sram support")
>>>
>>>The syntax is:
>>>
>>>Fixes: 6db92cc9d07d ("powerpc/85xx: add cache-sram support")
>>>
>>>> Cc: stable <stable at vger.kernel.org>
>>>
>>>The commit above went into v2.6.37.
>>>
>>>So no one has noticed this bug since then, how? Or did something else
>>>change to expose the problem?
>>
>> Actually a hard question to answer cause it also left me scratching for long.
>> However, I can not find right or definite answer.
>
>Oh, actually it's fairly straight forward, the code can't be built at
>all in upstream because CONFIG_FSL_85XX_CACHE_SRAM is not selectable or
>selected by anything.

Yeah, sure that is the reason, and I meant it was hard to figure out why
nobody had ever compiled the driver with FSL_85XX_CACHE_SRAM enabled
until me.
>
>You sent a patch previously to make it selectable, which Scott thought
>was a bad idea.
>
>So this whole file is dead code as far as I'm concerned, so patches for
>it definitely do not need to go to stable.
>
>If you want to add a user for it then please send a series doing that,
>and this commit can be the first.

For this, as you mentioned, it is dead and do not need to be applied to any stable.
And I recommand the patch as a unit itself cause our module which uses
it is still under developing, and the module itself would be taken as a
complete logical block. Also it would take some time.

Thanks, Wenhu
>
>cheers