From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Date: 2020-03-17 19:22:13
To:"王文虎" <wenhu.wang@xxxxxxxx>
cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>,Paul Mackerras <paulus@xxxxxxxxx>,Allison Randal <allison@xxxxxxxxxxx>,Richard Fontana <rfontana@xxxxxxxxxx>,Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>,Thomas Gleixner <tglx@xxxxxxxxxxxxx>,linuxppc-dev@xxxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx,trivial@xxxxxxxxxx,kernel@xxxxxxxx,stable <stable@xxxxxxxxxxxxxxx>
Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>王文虎 <wenhu.wang@xxxxxxxx> writes:
>> From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Date: 2020-03-16 17:41:12
>> To:WANG Wenhu <wenhu.wang@xxxxxxxx>,Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>,Paul Mackerras <paulus@xxxxxxxxx>,WANG Wenhu <wenhu.wang@xxxxxxxx>,Allison Randal <allison@xxxxxxxxxxx>,Richard Fontana <rfontana@xxxxxxxxxx>,Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>,Thomas Gleixner <tglx@xxxxxxxxxxxxx>,linuxppc-dev@xxxxxxxxxxxxxxxx,linux-kernel@xxxxxxxxxxxxxxx
>> cc: trivial@xxxxxxxxxx,kernel@xxxxxxxx,stable <stable@xxxxxxxxxxxxxxx>
>> Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>WANG Wenhu <wenhu.wang@xxxxxxxx> 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@xxxxxxxxxxxxxxx>
>>>
>>>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
