Re: Bug 205201 - Booting halts if Dawicontrol DC-2976 UW SCSI board installed, unless RAM size limited to 3500M

Christian Zigotzky
2019-11-26T12:00:23Z

On 25 November 2019 at 10:32 am, Mike Rapoport wrote:
> On Mon, Nov 25, 2019 at 08:39:23AM +0100, Christoph Hellwig wrote:
>> On Sat, Nov 23, 2019 at 12:42:27PM +0100, Christian Zigotzky wrote:
>>> Hello Christoph,
>>>
>>> Please find attached the dmesg of your Git kernel.
>> Thanks. It looks like on your platform the swiotlb buffer isn't
>> actually addressable based on the bus dma mask limit, which is rather
>> interesting. swiotlb_init uses memblock_alloc_low to allocate the
>> buffer, and I'll need some help from Mike and the powerpc maintainers
>> to figure out how that select where to allocate the buffer from, and
>> how we can move it to a lower address. My gut feeling would be to try
>> to do what arm64 does and define a new ARCH_LOW_ADDRESS_LIMIT, preferably
>> without needing too much arch specific magic.
> Presuming the problem is relevant for all CoreNet boards something like
> this could work:
>
> diff --git a/arch/powerpc/include/asm/dma.h b/arch/powerpc/include/asm/dma.h
> index 1b4f0254868f..7c6cfeeaff52 100644
> --- a/arch/powerpc/include/asm/dma.h
> +++ b/arch/powerpc/include/asm/dma.h
> @@ -347,5 +347,11 @@ extern int isa_dma_bridge_buggy;
> #define isa_dma_bridge_buggy (0)
> #endif
>
> +#ifdef CONFIG_CORENET_GENERIC
> +extern phys_addr_t ppc_dma_phys_limit;
> +#define ARCH_LOW_ADDRESS_LIMIT (ppc_dma_phys_limit - 1)
> +#endif
> +
> +
> #endif /* __KERNEL__ */
> #endif /* _ASM_POWERPC_DMA_H */
> diff --git a/arch/powerpc/platforms/85xx/common.c b/arch/powerpc/platforms/85xx/common.c
> index fe0606439b5a..346b436b6d3f 100644
> --- a/arch/powerpc/platforms/85xx/common.c
> +++ b/arch/powerpc/platforms/85xx/common.c
> @@ -126,3 +126,7 @@ void __init mpc85xx_qe_par_io_init(void)
> }
> }
> #endif
> +
> +#ifdef CONFIG_CORENET_GENERIC
> +phys_addr_t ppc_dma_phys_limit = 0xffffffffUL;
> +#endif
> diff --git a/arch/powerpc/platforms/85xx/corenet_generic.c b/arch/powerpc/platforms/85xx/corenet_generic.c
> index 7ee2c6628f64..673bcbdc7c75 100644
> --- a/arch/powerpc/platforms/85xx/corenet_generic.c
> +++ b/arch/powerpc/platforms/85xx/corenet_generic.c
> @@ -64,7 +64,7 @@ void __init corenet_gen_setup_arch(void)
> mpc85xx_smp_init();
>
> swiotlb_detect_4g();
> -
> + ppc_dma_phys_limit = 0x0fffffffUL;
> pr_info("%s board\n", ppc_md.name);
>
> mpc85xx_qe_init();
Hello Mike,

My PCI TV card works also with your patch! Before I had to add "#include
<asm/dma.h>" to the file "arch/powerpc/platforms/85xx/corenet_generic.c"
because of the following error:

------

CC      arch/powerpc/platforms/85xx/corenet_generic.o
CC      ipc/util.o
CC      ipc/msgutil.o
arch/powerpc/platforms/85xx/corenet_generic.c: In function
‘corenet_gen_setup_arch’:
arch/powerpc/platforms/85xx/corenet_generic.c:77:2: error:
‘ppc_dma_phys_limit’ undeclared (first use in this function); did you
mean ‘cpu_to_phys_id’?
ppc_dma_phys_limit = 0x0fffffffUL;
^~~~~~~~~~~~~~~~~~
cpu_to_phys_id
arch/powerpc/platforms/85xx/corenet_generic.c:77:2: note: each
undeclared identifier is reported only once for each function it appears in
scripts/Makefile.build:265: recipe for target
'arch/powerpc/platforms/85xx/corenet_generic.o' failed
make[3]: *** [arch/powerpc/platforms/85xx/corenet_generic.o] Error 1
scripts/Makefile.build:509: recipe for target
'arch/powerpc/platforms/85xx' failed
make[2]: *** [arch/powerpc/platforms/85xx] Error 2
scripts/Makefile.build:509: recipe for target 'arch/powerpc/platforms'
failed
make[1]: *** [arch/powerpc/platforms] Error 2
Makefile:1652: recipe for target 'arch/powerpc' failed
make: *** [arch/powerpc] Error 2

------

After that I was able to compile the latest Git kernel with your patch.

Thanks,
Christian