From: Larry Finger <Larry.Finger@lwfinger.net>
To: Christoph Hellwig <hch@lst.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
Christian Zigotzky <chzigotzky@xenosoft.de>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [BISECTED REGRESSION] b43legacy broken on G4 PowerBook
Date: Thu, 6 Jun 2019 15:11:55 -0500 [thread overview]
Message-ID: <1a9e2b2f-b388-bc13-3b90-9d6b4038073b@lwfinger.net> (raw)
In-Reply-To: <20190606114325.GA7497@lst.de>
On 6/6/19 6:43 AM, Christoph Hellwig wrote:
> On Thu, Jun 06, 2019 at 08:57:49PM +1000, Benjamin Herrenschmidt wrote:
>>> Wow... that's an odd amount. One thing we could possibly do is add code
>>> to limit the amount of RAM when we detect that device....
>>
>> Sent too quickly... I mean that *or* force swiotlb at 30-bits on those systems based
>> on detecting the presence of that device in the device-tree.
>
> swiotlb doesn't really help you, as these days swiotlb on matters for
> the dma_map* case. What would help is a ZONE_DMA that covers these
> devices. No need to do the 24-bit x86 does, but 30-bit would do it.
>
> WIP patch for testing below:
>
> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> index b8286a2013b4..7a367ce87c41 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -319,6 +319,10 @@ struct vm_area_struct;
> #endif /* __ASSEMBLY__ */
> #include <asm/slice.h>
>
> +#if 1 /* XXX: pmac? dynamic discovery? */
> +#define ARCH_ZONE_DMA_BITS 30
> +#else
> #define ARCH_ZONE_DMA_BITS 31
> +#endif
>
> #endif /* _ASM_POWERPC_PAGE_H */
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index cba29131bccc..2540d3b2588c 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -248,7 +248,8 @@ void __init paging_init(void)
> (long int)((top_of_ram - total_ram) >> 20));
>
> #ifdef CONFIG_ZONE_DMA
> - max_zone_pfns[ZONE_DMA] = min(max_low_pfn, 0x7fffffffUL >> PAGE_SHIFT);
> + max_zone_pfns[ZONE_DMA] = min(max_low_pfn,
> + ((1UL << ARCH_ZONE_DMA_BITS) - 1) >> PAGE_SHIFT);
> #endif
> max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
> #ifdef CONFIG_HIGHMEM
>
This trial patch failed.
Larry
next prev parent reply other threads:[~2019-06-06 20:13 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 22:50 [BISECTED REGRESSION] b43legacy broken on G4 PowerBook Aaro Koskinen
2019-06-06 0:54 ` Benjamin Herrenschmidt
2019-06-06 9:31 ` Aaro Koskinen
2019-06-06 10:56 ` Benjamin Herrenschmidt
2019-06-06 10:57 ` Benjamin Herrenschmidt
2019-06-06 11:43 ` Christoph Hellwig
2019-06-06 19:26 ` Larry Finger
2019-06-06 20:11 ` Larry Finger [this message]
2019-06-06 3:06 ` Larry Finger
2019-06-06 6:40 ` Christoph Hellwig
2019-06-07 17:25 ` Larry Finger
2019-06-07 17:29 ` Christoph Hellwig
2019-06-07 18:50 ` Larry Finger
2019-06-08 21:52 ` Larry Finger
2019-06-10 8:18 ` Christoph Hellwig
2019-06-10 16:09 ` Larry Finger
2019-06-11 6:05 ` Christoph Hellwig
2019-06-11 22:20 ` Larry Finger
2019-06-11 22:46 ` Aaro Koskinen
2019-06-12 1:57 ` Larry Finger
2019-06-11 22:46 ` Benjamin Herrenschmidt
2019-06-12 1:52 ` Larry Finger
2019-06-12 3:32 ` Benjamin Herrenschmidt
2019-06-12 6:55 ` Christoph Hellwig
2019-06-12 19:41 ` Larry Finger
2019-06-12 21:59 ` Benjamin Herrenschmidt
2019-06-13 7:29 ` Christoph Hellwig
2019-06-11 17:48 ` Andreas Schwab
2019-06-08 4:21 ` Benjamin Herrenschmidt
2019-06-08 7:23 ` Christoph Hellwig
2019-06-10 18:44 ` Larry Finger
2019-06-11 5:56 ` Benjamin Herrenschmidt
2019-06-11 6:08 ` Christoph Hellwig
2019-06-11 6:58 ` Benjamin Herrenschmidt
2019-06-11 6:59 ` Benjamin Herrenschmidt
2019-06-11 7:54 ` Christoph Hellwig
2019-06-11 9:04 ` Benjamin Herrenschmidt
2019-06-11 7:53 ` Christoph Hellwig
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