linux-kernel - [PATCH 1/5] firewire: ohci: use common macro to interpret be32 data in le32 buffer

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Date: Wed,  3 Jul 2024 07:20:30 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] firewire: ohci: use common macro to interpret be32 data in le32 buffer

The 1394 OHCI driver configures the hardware to transfer the data quadlets
of packet via DMA after converting it to little endian, therefore the data
is typed as __le32. Nevertheless some actual hardware ignores the
configuration. In the case, the data in DMA buffer is aligned to big endian
(__be32).

For the case in big-endian machine, the driver includes the following
interpretation from __le32 to u32 (host-endian = __be32):

    * (__force __u32)(v)

In include/linux/byteorder/generic.h, be32_to_cpu() is available. It is
expanded to the following expression in
'include/uapi/linux/byteorder/big_endian.h':

    * (__force __u32)(__be32)(x)

This commit replace the ad-hoc endian interpretation with the above.

Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
 drivers/firewire/ohci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index df16a8f4ee7f..a2d6d1d1ec2b 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -876,7 +876,7 @@ static void ar_sync_buffers_for_cpu(struct ar_context *ctx,

 #if defined(CONFIG_PPC_PMAC) && defined(CONFIG_PPC32)
 #define cond_le32_to_cpu(v) \
-	(ohci->quirks & QUIRK_BE_HEADERS ? (__force __u32)(v) : le32_to_cpu(v))
+	(ohci->quirks & QUIRK_BE_HEADERS ? be32_to_cpu(v) : le32_to_cpu(v))
 #else
 #define cond_le32_to_cpu(v) le32_to_cpu(v)
 #endif
-- 
2.43.0