RE: [PATCH v2 2/4] rtc: pcf85363: Add support for NXP pcf85263 rtc

[Biju Das <biju.das@bp.renesas.com>]

Hi Geert and Alexandre,

Thanks for the feedback.

> Subject: Re: [PATCH v2 2/4] rtc: pcf85363: Add support for NXP pcf85263 rtc
>
> Hi Alexandre,
>
> On Fri, Nov 30, 2018 at 1:32 PM Alexandre Belloni
> <alexandre.belloni@bootlin.com> wrote:
> > On 30/11/2018 12:05:16+0100, Geert Uytterhoeven wrote:
> > > On Thu, Nov 29, 2018 at 6:03 PM Biju Das <biju.das@bp.renesas.com>
> wrote:
> > > > Add support for NXP pcf85263 real-time clock. pcf85263 rtc is
> > > > compatible with pcf85363,except that pcf85363 has additional 64 bytes
> of RAM.
> > > >
> > > > 1 byte of nvmem is supported and exposed in sysfs (# is the
> > > > instance number,starting with 0):
> > > > /sys/bus/nvmem/devices/pcf85x63-#/nvmem
> > > >
> > > > Signed-off-by: Biju Das <biju.das@bp.renesas.com>
> > > > ---
> > > >  V1-->V2 Incorporated Alexandre and Geert's review comment.
> > >
> > > Thanks for the update!
> > >
> > > > --- a/drivers/rtc/rtc-pcf85363.c
> > > > +++ b/drivers/rtc/rtc-pcf85363.c
> > >
> > > > @@ -321,15 +344,25 @@ static int pcf85363_probe(struct i2c_client
> *client,
> > > >                           const struct i2c_device_id *id)  {
> > > >         struct pcf85363 *pcf85363;
> > > > -       struct nvmem_config nvmem_cfg = {
> > > > -               .name = "pcf85363-",
> > > > -               .word_size = 1,
> > > > -               .stride = 1,
> > > > -               .size = NVRAM_SIZE,
> > > > -               .reg_read = pcf85363_nvram_read,
> > > > -               .reg_write = pcf85363_nvram_write,
> > > > +       const struct regmap_config *regmap_config =
> &pcf_85363_regmap_config;
> > > > +       struct nvmem_config nvmem_cfg[] = {
> > >
> > > static?
> > >
> > > Although the nvmem_config is copied, and thus static is not needed,
> > > I guess using static will decrease kernel size.
> > >
> >
> > Hum, I don't think, this is on the stack anyway.
>
> If you make it static, it's no longer allocated on the stack, and gcc has no
> longer to emit code to initialize all members.
>

I have used "size" command to check the size of vmlinux with and without static. Please find the results.

Without static
===========
$ size vmlinux
   text   data    bss    dec    hexfilename
71473602625982 29260810065950 99981evmlinux

With static variable
==================
$ size vmlinux
   text   data    bss    dec    hexfilename
71472002626110 29260810065918 9997fevmlinux

So overall with static, there is a reduction in kernel size. I will send V3 with declaring it as static.

Regards,
Biju


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