Hi Andrew,
On Mon, Mar 23, 2015 at 03:33:34PM -0700, Andrew Morton wrote:
> On Mon, 23 Mar 2015 15:28:54 +0200 Baruch Siach <baruch@xxxxxxxxxx> wrote:
> > Add driver for the RTC hardware block on the Conexant CX92755 SoC, from
> > the
> > Digicolor series of SoCs. Tested on the Equinox evaluation board for the
> > CX92755 chip.
> >
> > ...
> >
> > +static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
> > +{
> > + u8 read_cmds[] = {CMD_READ, CMD_NOP};
> > + u32 reference, time1, time2;
> > + int ret;
> > +
> > + ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
>
> This is asking the compiler to build read_cmds[] on the stack each time
> dc_rtc_read() is called.
>
> If we instead create the array at compile time:
>
> +++ a/drivers/rtc/rtc-digicolor.c
> @@ -42,7 +42,7 @@ struct dc_rtc {
> void __iomem *regs;
> };
>
> -static int dc_rtc_cmds(struct dc_rtc *rtc, u8 *cmds, int len)
> +static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
> {
> u8 val;
> int i, ret;
> @@ -62,7 +62,7 @@ static int dc_rtc_cmds(struct dc_rtc *rt
>
> static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
> {
> - u8 read_cmds[] = {CMD_READ, CMD_NOP};
> + static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
> u32 reference, time1, time2;
> int ret;
>
> @@ -86,7 +86,7 @@ static int dc_rtc_read(struct dc_rtc *rt
>
> static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
> {
> - u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
> + static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
>
> writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
> return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
>
> The code gets a bit smaller and faster:
>
> text data bss dec hex filename
> 1628 400 512 2540 9ec drivers/rtc/rtc-digicolor.o-before
> 1593 400 536 2529 9e1 drivers/rtc/rtc-digicolor.o-after
Thanks for the tip, and for taking the driver through your tree.
baruch
--
http://baruch.siach.name/blog/ ~. .~ Tk Open Systems
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- baruch@xxxxxxxxxx - tel: +972.2.679.5364, http://www.tkos.co.il -
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