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

From: Michael Ellerman <mpe@ellerman.id.au>
 Date: 2020-03-17 19:22:13
To:"王文虎" [off-list ref]
 cc: Benjamin Herrenschmidt [off-list ref],Paul Mackerras [off-list ref],Allison Randal [off-list ref],Richard Fontana [off-list ref],Greg Kroah-Hartman [off-list ref],Thomas Gleixner [off-list ref],linuxppc-dev@lists.ozlabs.org,linux-kernel@vger.kernel.org,trivial@kernel.org,kernel@vivo.com,stable [off-list ref]
Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>王文虎 [off-list ref] writes:

quoted

From: Michael Ellerman <mpe@ellerman.id.au>
 Date: 2020-03-16 17:41:12
To:WANG Wenhu [off-list ref],Benjamin Herrenschmidt [off-list ref],Paul Mackerras [off-list ref],WANG Wenhu [off-list ref],Allison Randal [off-list ref],Richard Fontana [off-list ref],Greg Kroah-Hartman [off-list ref],Thomas Gleixner [off-list ref],linuxppc-dev@lists.ozlabs.org,linux-kernel@vger.kernel.org
 cc: trivial@kernel.org,kernel@vivo.com,stable [off-list ref]
Subject: Re: [PATCH v3] powerpc/fsl-85xx: fix compile error>WANG Wenhu [off-list ref] writes:

quoted

quoted

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")

quoted

Cc: stable <redacted>

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