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From: Larry Finger <Larry.Finger@lwfinger.net>
To: Aaro Koskinen <aaro.koskinen@iki.fi>,
	Christoph Hellwig <hch@lst.de>,
	Christian Zigotzky <chzigotzky@xenosoft.de>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [BISECTED REGRESSION] b43legacy broken on G4 PowerBook
Date: Wed, 5 Jun 2019 22:06:18 -0500	[thread overview]
Message-ID: <35b3f09b-b371-e2cc-4436-120c67e2f1fb@lwfinger.net> (raw)
In-Reply-To: <20190605225059.GA9953@darkstar.musicnaut.iki.fi>

On 6/5/19 5:50 PM, Aaro Koskinen wrote:
> Hi,
> 
> When upgrading from v5.0 -> v5.1 on G4 PowerBook, I noticed WLAN does
> not work anymore:
> 
> [   42.004303] b43legacy-phy0: Loading firmware version 0x127, patch level 14 (2005-04-18 02:36:27)
> [   42.184837] b43legacy-phy0 debug: Chip initialized
> [   42.184873] b43legacy-phy0 ERROR: The machine/kernel does not support the required 30-bit DMA mask
> 
> The same happens with the current mainline.
> 
> Bisected to:
> 
> 	commit 65a21b71f948406201e4f62e41f06513350ca390
> 	Author: Christoph Hellwig <hch@lst.de>
> 	Date:   Wed Feb 13 08:01:26 2019 +0100
> 
> 	    powerpc/dma: remove dma_nommu_dma_supported
> 
> 	    This function is largely identical to the generic version used
> 	    everywhere else.  Replace it with the generic version.
> 
> 	    Signed-off-by: Christoph Hellwig <hch@lst.de>
> 	    Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
> 	    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Aaro,

First of all, you have my sympathy for the laborious bisection on a PowerBook 
G4. I have done several myself. Thank you.

I confirm your results.

The ppc code has a maximum DMA size of 31 bits, thus a 32-bit request will fail. 
Why the 30-bit fallback fails in b43legacy fails while it works in b43 is a mystery.

Although dma_nommu_dma_supported() may be "largely identical" to 
dma_direct_supported(), they obviously differ. Routine dma_nommu_dma_supported() 
returns 1 for 32-bit systems, but I do not know what dma_direct_supported() returns.

I am trying to find a patch.

Larry

  parent reply	other threads:[~2019-06-06  3:07 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
2019-06-06  3:06 ` Larry Finger [this message]
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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