Re: [PATCH linux-next v3 4/4] clocksource/drivers/timer-mediatek: Make timer-mediatek become loadable module

[Walter Chang (張維哲)]

On Wed, 2023-04-19 at 10:10 +0200, AngeloGioacchino Del Regno wrote:
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> 
> 
> Il 19/04/23 09:49, walter.chang@xxxxxxxxxxxx ha scritto:
> > From: Chun-Hung Wu <chun-hung.wu@xxxxxxxxxxxx>
> > 
> > Make the timer-mediatek driver which can register
> > an always-on timer as tick_broadcast_device on
> > MediaTek SoCs become loadable module in GKI.
> > 
> > Tested-by: Walter Chang <walter.chang@xxxxxxxxxxxx>
> > Signed-off-by: Chun-Hung Wu <chun-hung.wu@xxxxxxxxxxxx>
> 
> I think I typoed your email when sending the example patch for the
> conversion to platform_device. Check [1], it may be better to just
> iterate through that? (please ignore the pure_initcall() part, that's
> a mistake, it's never gonna happen as it automatically becomes a
> module_init() call).
> 
> It depends on what maintainers think about that clocksource.h
> addition,
> the patch got zero comments, so if you're interested in that perhaps
> we
> can explicitly ask what would be the best option between yours and
> mine;
> that addition is done only to avoid the big ifdef party that this
> patch
> proposes and makes things a bit shorter if this timer modularization
> goes on with more drivers, but I don't have strong opinions anyway.
> 
> In the meanwhile, just to eventually speed up integrating this, or
> the
> other patch - I'll still give you a review of this one.
> 
> [1]:
> 
https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/patch/20230309132119.175650-1-angelogioacchino.delregno@xxxxxxxxxxxxx/__;!!CTRNKA9wMg0ARbw!kellIP9qWQwZCUsbK9-s9WForDbz_5-CAGdMIzYbGSXgvXjVGnyGmlmGHeKEbXr_URQeKVHnb6eFAh-fBshGD1KTERh-mzSAlQ$

Thank you for providing an alternative implementation to make the timer
driver loadable. We will study whether this solution is feasible.

> 
> > ---
> >   drivers/clocksource/Kconfig          |  2 +-
> >   drivers/clocksource/timer-mediatek.c | 39
> > ++++++++++++++++++++++++++++
> >   2 files changed, 40 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/clocksource/Kconfig
> > b/drivers/clocksource/Kconfig
> > index 526382dc7482..a7413ad7b6ad 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -472,7 +472,7 @@ config SYS_SUPPORTS_SH_CMT
> >       bool
> > 
> >   config MTK_TIMER
> > -     bool "Mediatek timer driver" if COMPILE_TEST
> > +     tristate "Mediatek timer driver"
> 
> While at it, you could also fix the text, Mediatek -> MediaTek
> 
> >       depends on HAS_IOMEM
> >       select TIMER_OF
> >       select CLKSRC_MMIO
> > diff --git a/drivers/clocksource/timer-mediatek.c
> > b/drivers/clocksource/timer-mediatek.c
> > index 7bcb4a3f26fb..3448848682c0 100644
> > --- a/drivers/clocksource/timer-mediatek.c
> > +++ b/drivers/clocksource/timer-mediatek.c
> > @@ -13,6 +13,9 @@
> >   #include <linux/clocksource.h>
> >   #include <linux/interrupt.h>
> >   #include <linux/irqreturn.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> >   #include <linux/sched_clock.h>
> >   #include <linux/slab.h>
> >   #include "timer-of.h"
> > @@ -337,5 +340,41 @@ static int __init mtk_gpt_init(struct
> > device_node *node)
> > 
> >       return 0;
> >   }
> > +
> > +#ifdef MODULE
> 
> #ifndef MODULE
> ... two lines...
> #else
> ... a bunch of lines ...
> #endif
> 
> looks more readable. I'd go with that.
> 
> > +static int mtk_timer_probe(struct platform_device *pdev)
> > +{
> > +     int (*timer_init)(struct device_node *node);
> > +     struct device_node *np = pdev->dev.of_node;
> > +
> > +     timer_init = of_device_get_match_data(&pdev->dev);
> > +     return timer_init(np);
> > +}
> > +
> > +static const struct of_device_id mtk_timer_match_table[] = {
> > +     {
> > +             .compatible = "mediatek,mt6577-timer",
> > +             .data = mtk_gpt_init,
> 
> Fits in one line!
> 
> > +     },
> > +     {
> > +             .compatible = "mediatek,mt6765-timer",
> > +             .data = mtk_syst_init,
> 
> ditto.
> 
> > +     },
> > +     {}
> 
> Always end with { /* sentinel */ }
> 
> > +};
> > +
> > +static struct platform_driver mtk_timer_driver = {
> > +     .probe = mtk_timer_probe,
> > +     .driver = {
> > +             .name = "mtk-timer",
> 
> "mediatek-timer" looks nicer :-)
> 
> > +             .of_match_table = mtk_timer_match_table,
> > +     },
> > +};
> > +module_platform_driver(mtk_timer_driver);
> > +
> > +MODULE_DESCRIPTION("MediaTek Module Timer driver");
> 
> "MediaTek Timer driver" is enough, "Module" gets misleading if this
> gets compiled
> as built in platform driver (instead of built in timer_of).
> 

Thanks for your review, I will fix these in next patch.

Best regards,
Walter Chang