[PATCH] net: sparx5: fix bitmask check

[PATCH] net: sparx5: fix bitmask check

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Older compilers such as gcc-5.5 produce a warning in this driver
when ifh_encode_bitfield() is not getting inlined:

drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c: In function 'ifh_encode_bitfield':
include/linux/compiler_types.h:333:38: error: call to '__compiletime_assert_545' declared with attribute error: Unsupported width, must be <= 40
drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c:28:2: note: in expansion of macro 'compiletime_assert'
  compiletime_assert(width <= 40, "Unsupported width, must be <= 40");
  ^

Mark the function as __always_inline to make the check work correctly
on all compilers. To make this also work on 32-bit architectures, change
the GENMASK() to GENMASK_ULL().

Fixes: f3cad2611a77 ("net: sparx5: add hostmode with phylink support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c b/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
index 9d485a9d1f1f..6f362f6708c6 100644
--- a/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
+++ b/drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c
@@ -13,14 +13,15 @@
  */
 #define VSTAX 73
 
-static void ifh_encode_bitfield(void *ifh, u64 value, u32 pos, u32 width)
+static __always_inline void ifh_encode_bitfield(void *ifh, u64 value,
+						u32 pos, u32 width)
 {
 	u8 *ifh_hdr = ifh;
 	/* Calculate the Start IFH byte position of this IFH bit position */
 	u32 byte = (35 - (pos / 8));
 	/* Calculate the Start bit position in the Start IFH byte */
 	u32 bit  = (pos % 8);
-	u64 encode = GENMASK(bit + width - 1, bit) & (value << bit);
+	u64 encode = GENMASK_ULL(bit + width - 1, bit) & (value << bit);
 
 	/* Max width is 5 bytes - 40 bits. In worst case this will
 	 * spread over 6 bytes - 48 bits
-- 
2.29.2

Re: [PATCH] net: sparx5: fix bitmask check

[Jakub Kicinski]

On Mon,  2 Aug 2021 16:54:37 +0200 Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Older compilers such as gcc-5.5 produce a warning in this driver
> when ifh_encode_bitfield() is not getting inlined:
> 
> drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c: In function 'ifh_encode_bitfield':
> include/linux/compiler_types.h:333:38: error: call to '__compiletime_assert_545' declared with attribute error: Unsupported width, must be <= 40
> drivers/net/ethernet/microchip/sparx5/sparx5_netdev.c:28:2: note: in expansion of macro 'compiletime_assert'
>   compiletime_assert(width <= 40, "Unsupported width, must be <= 40");
>   ^
> 
> Mark the function as __always_inline to make the check work correctly
> on all compilers. 

I fixed this by moving the check out to a macro wrapper in net:
6387f65e2acb ("net: sparx5: fix compiletime_assert for GCC 4.9")

> To make this also work on 32-bit architectures, change
> the GENMASK() to GENMASK_ULL().

Would you mind resending just that part against net/master?

> Fixes: f3cad2611a77 ("net: sparx5: add hostmode with phylink support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Re: [PATCH] net: sparx5: fix bitmask check

[Arnd Bergmann]

On Mon, Aug 2, 2021 at 5:02 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> I fixed this by moving the check out to a macro wrapper in net:
> 6387f65e2acb ("net: sparx5: fix compiletime_assert for GCC 4.9")

Ok, got it.

> > To make this also work on 32-bit architectures, change
> > the GENMASK() to GENMASK_ULL().
>
> Would you mind resending just that part against net/master?

Done.

        Arnd