On 2015-03-16 17:59, Stephen Warren wrote:
> On 03/14/2015 06:05 PM, Stefan Agner wrote:
>> Optional fields are set to -1 by various preprocessor macros. Make
>> sure the struct fields can actually store them.
>
>> diff --git a/drivers/pinctrl/pinctrl-tegra.h b/drivers/pinctrl/pinctrl-tegra.h
>
>> - u32 mux_bit:6;
>> - u32 pupd_bit:6;
>> - u32 tri_bit:6;
> ...
>> + s8 mux_bit:6;
>> + s8 pupd_bit:6;
>> + s8 tri_bit:6;
>
> Could we make these s32s instead? According to the C standard, the
> type should be a signed or unsigned int, and s32 matches that better
> than s8 for existing Tegra 32-bit platforms. Equally, for bitfields
> that don't fit into the remaining space within a container (s8 above),
> implementations are allowed to either span bitfields across multiple
> containers, or pad the current container and start the bitfield in the
> next container. Using the larger s32 as the "container" yields less
> opportunity for potential padding and thus wasting space.
The reason I took the signed byte variant was that it gets filled into
that type later on. So I thought it would be kind of nice to see that
fact already in the definition of the struct...
But your argument has actual real significance. Will change that.
> Do you observe any increase in the sizes reported by
> "${CROSS_COMPILE}size pinctrl-tegra*.o" with this patch?
Baseline:
5406 180 1 5587
15d3 drivers/pinctrl/pinctrl-tegra-xusb.o
5244 64 0 5308 14bc drivers/pinctrl/pinctrl-tegra.o
18072 1032 0 19104
4aa0 drivers/pinctrl/pinctrl-tegra114.o
19214 1128 0 20342
4f76 drivers/pinctrl/pinctrl-tegra124.o
18352 876 0 19228
4b1c drivers/pinctrl/pinctrl-tegra20.o
24621 1068 0 25689
6459 drivers/pinctrl/pinctrl-tegra30.o
With the patch above...
text data bss dec hex filename
5406 180 1 5587
15d3 drivers/pinctrl/pinctrl-tegra-xusb.o
5252 64 0 5316 14c4 drivers/pinctrl/pinctrl-tegra.o
18932 1032 0 19964
4dfc drivers/pinctrl/pinctrl-tegra114.o
20142 1128 0 21270
5316 drivers/pinctrl/pinctrl-tegra124.o
18988 876 0 19864
4d98 drivers/pinctrl/pinctrl-tegra20.o
25781 1068 0 26849
68e1 drivers/pinctrl/pinctrl-tegra30.o
--
Stefan
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