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From: david.laight.linux@gmail.com
To: Yury Norov <yury.norov@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Crt Mori <cmo@melexis.com>,
	Richard Genoud <richard.genoud@bootlin.com>,
	Andy Shevchenko <andriy.shevchenko@intel.com>,
	Luo Jie <quic_luoj@quicinc.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, "David S . Miller" <davem@davemloft.net>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Andreas Noever <andreas.noever@gmail.com>,
	Yehezkel Bernat <YehezkelShB@gmail.com>,
	Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Cc: David Laight <david.laight.linux@gmail.com>
Subject: [PATCH v2 02/16] thunderbolt: Don't pass a bitfield to FIELD_GET
Date: Fri, 12 Dec 2025 19:37:07 +0000	[thread overview]
Message-ID: <20251212193721.740055-3-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20251212193721.740055-1-david.laight.linux@gmail.com>

From: David Laight <david.laight.linux@gmail.com>

None of sizeof(), typeof() or __auto_type can be used with bitfields
which makes it difficult to assign a #define parameter to a local
without promoting char and short to int.

Change:
	u32 thunderbolt_version:8;
to the equivalent:
	u8 thunderbolt_version;
(and the other three bytes of 'DWORD 4' to match).

This is necessary so that FIELD_GET can use sizeof() to verify 'reg'.

Signed-off-by: David Laight <david.laight.linux@gmail.com>
---

Changes for v2:
- Change structure definition instead of call to FIELD_GET().

FIELD_GET currently uses _Generic() which behaves differently for
gcc and clang (I suspect both are wrong!).
gcc treats 'u32 foo:8' as 'u8', but will take the 'default' for other
widths (which will generate an error in FIED_GET().
clang treats 'u32 foo:n' as 'u32'.

 drivers/thunderbolt/tb_regs.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index c0bf136236e6..f35f062beb34 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -180,14 +180,14 @@ struct tb_regs_switch_header {
 	u32 route_hi:31;
 	bool enabled:1;
 	/* DWORD 4 */
-	u32 plug_events_delay:8; /*
-				  * RW, pause between plug events in
-				  * milliseconds. Writing 0x00 is interpreted
-				  * as 255ms.
-				  */
-	u32 cmuv:8;
-	u32 __unknown4:8;
-	u32 thunderbolt_version:8;
+	u8 plug_events_delay; /*
+			       * RW, pause between plug events in
+			       * milliseconds. Writing 0x00 is interpreted
+			       * as 255ms.
+			       */
+	u8 cmuv;
+	u8 __unknown4;
+	u8 thunderbolt_version;
 } __packed;
 
 /* Used with the router thunderbolt_version */
-- 
2.39.5


  parent reply	other threads:[~2025-12-12 19:38 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-12 19:37 [PATCH v2 0/16] bitfield: tidy up bitfield.h david.laight.linux
2025-12-12 19:37 ` [PATCH v2 01/16] nfp: Call FIELD_PREP() in NFP_ETH_SET_BIT_CONFIG() wrapper david.laight.linux
2025-12-12 23:10   ` Jakub Kicinski
2025-12-12 19:37 ` david.laight.linux [this message]
2025-12-13  2:28   ` [PATCH v2 02/16] thunderbolt: Don't pass a bitfield to FIELD_GET Yury Norov
2025-12-13 10:01     ` David Laight
2025-12-13 22:14       ` David Laight
2025-12-12 19:37 ` [PATCH v2 03/16] bitmap: Use FIELD_PREP() in expansion of FIELD_PREP_WM16() david.laight.linux
2025-12-12 19:37 ` [PATCH v2 04/16] bitfield: Copy #define parameters to locals david.laight.linux
2025-12-12 19:37 ` [PATCH v2 05/16] bitfield: Merge __field_prep/get() into field_prep/get() david.laight.linux
2025-12-12 19:37 ` [PATCH v2 06/16] bitfield: Remove some pointless casts david.laight.linux
2025-12-12 19:37 ` [PATCH v2 07/16] bitfield: FIELD_MODIFY: Only do a single read/write on the target david.laight.linux
2025-12-12 19:37 ` [PATCH v2 08/16] bitfield: Simplify __BF_FIELD_CHECK_REG() david.laight.linux
2025-12-12 19:37 ` [PATCH v2 09/16] bitfield: Rename __FIELD_PREP/GET() to __BF_FIELD_PREP/GET() david.laight.linux
2025-12-12 19:37 ` [PATCH v2 10/16] bitfield: Split the 'val' check out of __BF_FIELD_CHECK_MASK() david.laight.linux
2025-12-12 19:37 ` [PATCH v2 11/16] bitfield: Common up validation of the mask parameter david.laight.linux
2025-12-14  6:19   ` kernel test robot
2025-12-14 13:17     ` David Laight
2025-12-12 19:37 ` [PATCH v2 12/16] bitfield: Remove leading _ from #define formal parameter names david.laight.linux
2025-12-12 19:37 ` [PATCH v2 13/16] bitfield: Reduce indentation david.laight.linux
2025-12-12 19:37 ` [PATCH v2 14/16] bitfield: Add comment block for the host/fixed endian functions david.laight.linux
2025-12-12 19:37 ` [PATCH v2 15/16] bitfield: Update comments for le/be functions david.laight.linux
2025-12-12 19:37 ` [PATCH v2 16/16] build_bug.h; Remove __BUILD_BUG_ON_NOT_POWER_OF_2() david.laight.linux

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