On Wed, Dec 06, 2017 at 08:01:52PM +0100, Geert Uytterhoeven wrote:
> Hi Kaneko-san,
>
> On Wed, Dec 6, 2017 at 7:48 PM, Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> wrote:
> > From: Hien Dang <hien.dang.eb@xxxxxxxxxxx>
> >
> > This patch adds an implementation that saves and restores the state of
> > GPIO configuration on suspend and resume.
> >
> > Signed-off-by: Hien Dang <hien.dang.eb@xxxxxxxxxxx>
> > Signed-off-by: Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>
> > Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx>
>
> Thanks for your patch!
>
> > --- a/drivers/gpio/gpio-rcar.c
> > +++ b/drivers/gpio/gpio-rcar.c
> > @@ -31,6 +31,16 @@
> > #include <linux/spinlock.h>
> > #include <linux/slab.h>
> >
> > +struct gpio_rcar_bank_info {
> > + bool iointsel;
> > + bool inoutsel;
> > + bool outdt;
> > + bool active_high_rising_edge;
> > + bool level_trigger;
> > + bool both;
> > + bool intmsk;
> > +};
>
> So for each GPIO, you save 7 bools = 7 bytes.
s/save/use/ ?
> > struct gpio_rcar_priv {
> > void __iomem *base;
> > spinlock_t lock;
> > @@ -41,6 +51,7 @@ struct gpio_rcar_priv {
> > unsigned int irq_parent;
> > bool has_both_edge_trigger;
> > bool needs_clk;
> > + struct gpio_rcar_bank_info bank_info[32];
>
> That's 32 x 7 = 224 bytes in total.
>
> What about just using 7 u32s instead, one for each register to save?
> That way you only need 7 x 4 = 28 bytes, and you can probably optimize
> the code to just save/restore the whole register at once.
So the suggestion is to use a u32 instead of struct gpio_rcar_bank_info,
and for each field of struct gpio_rcar_bank_info use a bit in the u32?
If so, probably one could go a step further and use a u8 as there are
currently only 7 fields, thus using 32 x 1 = 32 bytes rather than
32 x 4 = 128 bytes.
