Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [BISECTED REGRESSION] b43legacy broken on G4 PowerBook
To:     Aaro Koskinen <aaro.koskinen@iki.fi>,
        Christoph Hellwig <hch@lst.de>,
        Christian Zigotzky <chzigotzky@xenosoft.de>,
        Michael Ellerman <mpe@ellerman.id.au>
Cc:     linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
References: <20190605225059.GA9953@darkstar.musicnaut.iki.fi>
From:   Larry Finger <Larry.Finger@lwfinger.net>
Message-ID: <73da300c-871c-77ac-8a3a-deac226743ef@lwfinger.net>
Date:   Fri, 7 Jun 2019 12:25:54 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.0
MIME-Version: 1.0
In-Reply-To: <20190605225059.GA9953@darkstar.musicnaut.iki.fi>
Content-Type: multipart/mixed;
 boundary="------------248DB5856E99694593DD245B"
Content-Language: en-US
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

This is a multi-part message in MIME format.
--------------248DB5856E99694593DD245B
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit

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,

Please try the attached patch. I'm not really pleased with it and I will 
continue to determine why the fallback to a 30-bit mask fails, but at least this 
one works for me.

Larry


--------------248DB5856E99694593DD245B
Content-Type: text/x-patch;
 name="0001-b43legacy-Fix-DMA-breakage-from-commit-commit-65a21b.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename*0="0001-b43legacy-Fix-DMA-breakage-from-commit-commit-65a21b.pa";
 filename*1="tch"

From 25e2f50273e785598b6bd9a8aee28cf825d3fe9f Mon Sep 17 00:00:00 2001
From: Larry Finger <Larry.Finger@lwfinger.net>
Date: Fri, 7 Jun 2019 12:04:16 -0500
Subject: [PATCH] b43legacy: Fix DMA breakage from commit commit 65a21b71f948
To: kvalo@codeaurora.org
Cc: linux-wireless@vger.kernel.org,
    pkshih@realtek.com

Following commit 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported"),
this driver errors with a message that "The machine/kernel does not
support the required 30-bit DMA mask." Indeed, the hardware only allows
31-bit masks. This solution is to change the fallback mask from 30-
to 31-bits for 32-bit PPC systems.

Fixes: 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported")
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
---
 drivers/net/wireless/broadcom/b43legacy/dma.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/dma.c b/drivers/net/wireless/broadcom/b43legacy/dma.c
index 1cc25f44dd9a..75613f516e50 100644
--- a/drivers/net/wireless/broadcom/b43legacy/dma.c
+++ b/drivers/net/wireless/broadcom/b43legacy/dma.c
@@ -27,6 +27,15 @@
 #include <linux/slab.h>
 #include <net/dst.h>
 
+/* Special handling for PPC32 - The maximum DMA mask is 31 bits, and
+ * the fallback to 30 bits fails. Set the fallback at 31.
+ */
+#ifdef CONFIG_PPC32
+#define FB_DMA	31
+#else
+#define FB_DMA	30
+#endif
+
 /* 32bit DMA ops. */
 static
 struct b43legacy_dmadesc32 *op32_idx2desc(struct b43legacy_dmaring *ring,
@@ -418,7 +427,7 @@ static bool b43legacy_dma_mapping_error(struct b43legacy_dmaring *ring,
 
 	switch (ring->type) {
 	case B43legacy_DMA_30BIT:
-		if ((u64)addr + buffersize > (1ULL << 30))
+		if ((u64)addr + buffersize > (1ULL << FB_DMA))
 			goto address_error;
 		break;
 	case B43legacy_DMA_32BIT:
@@ -617,12 +626,12 @@ static u64 supported_dma_mask(struct b43legacy_wldev *dev)
 	if (tmp & B43legacy_DMA32_TXADDREXT_MASK)
 		return DMA_BIT_MASK(32);
 
-	return DMA_BIT_MASK(30);
+	return DMA_BIT_MASK(FB_DMA);
 }
 
 static enum b43legacy_dmatype dma_mask_to_engine_type(u64 dmamask)
 {
-	if (dmamask == DMA_BIT_MASK(30))
+	if (dmamask == DMA_BIT_MASK(FB_DMA))
 		return B43legacy_DMA_30BIT;
 	if (dmamask == DMA_BIT_MASK(32))
 		return B43legacy_DMA_32BIT;
@@ -802,7 +811,7 @@ static int b43legacy_dma_set_mask(struct b43legacy_wldev *dev, u64 mask)
 			continue;
 		}
 		if (mask == DMA_BIT_MASK(32)) {
-			mask = DMA_BIT_MASK(30);
+			mask = DMA_BIT_MASK(FB_DMA);
 			fallback = true;
 			continue;
 		}
-- 
2.21.0


--------------248DB5856E99694593DD245B--