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Date:	Thu, 22 May 2014 12:57:27 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Zhang Rui <rui.zhang@...el.com>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	bhelgaas@...gle.com, matthew.garrett@...ula.com,
	rafael.j.wysocki@...el.com, dmitry.torokhov@...il.com
Subject: Re: [PATCH V6 07/11] ACPI: introduce dummy lpss scan handler

On Wed, May 21, 2014 at 10:56:59PM +0800, Zhang Rui wrote:
> On δΈ‰, 2014-05-21 at 11:48 +0300, Mika Westerberg wrote:
> > On Thu, May 15, 2014 at 02:44:12PM +0800, Zhang Rui wrote:
> > > The new ACPI device enumeration mechanism, which will be introduced
> > > in a later patch, will enumerate the _HID devices w/o any scan
> > > handler attached to platform bus.
> > > This means that, for the devices that are attached to a configurable
> > > scan handler, we should make sure no platform devices would be
> > > created for them even if the scan handler is compiled out.
> > > 
> > > Fix this problem for lpss devices by introducing a dummy
> > > lpss scan handler in this patch.
> > > 
> > > Plus, if lpt_clk_init() fails, we need this dummy scan handler as well.
> > > 
> > > Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> > > ---
> > >  drivers/acpi/Makefile    |  2 +-
> > >  drivers/acpi/acpi_lpss.c | 69 ++++++++++++++++++++++++++++++++++--------------
> > >  drivers/acpi/internal.h  |  4 ---
> > >  3 files changed, 50 insertions(+), 25 deletions(-)
> > > 
> > > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > > index 171efc2..605eff7 100644
> > > --- a/drivers/acpi/Makefile
> > > +++ b/drivers/acpi/Makefile
> > > @@ -39,7 +39,7 @@ acpi-y				+= processor_core.o
> > >  acpi-y				+= ec.o
> > >  acpi-$(CONFIG_ACPI_DOCK)	+= dock.o
> > >  acpi-y				+= pci_root.o pci_link.o pci_irq.o
> > > -acpi-$(CONFIG_X86_INTEL_LPSS)	+= acpi_lpss.o
> > > +acpi-y				+= acpi_lpss.o
> > >  acpi-y				+= acpi_platform.o
> > >  acpi-y				+= acpi_pnp.o
> > >  acpi-y				+= power.o
> > > diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
> > > index 69e29f4..965428f 100644
> > > --- a/drivers/acpi/acpi_lpss.c
> > > +++ b/drivers/acpi/acpi_lpss.c
> > > @@ -24,6 +24,8 @@
> > >  
> > >  ACPI_MODULE_NAME("acpi_lpss");
> > >  
> > > +#ifdef CONFIG_X86_INTEL_LPSS
> > > +
> > >  #define LPSS_CLK_SIZE	0x04
> > >  #define LPSS_LTR_SIZE	0x18
> > >  
> > > @@ -159,40 +161,50 @@ static struct lpss_device_desc byt_i2c_dev_desc = {
> > >  	.shared_clock = &i2c_clock,
> > >  };
> > >  
> > > +#define LPSS_PTR(desc) ((unsigned long)&desc)
> > > +
> > > +#else
> > > +
> > > +#define LPSS_PTR(desc) 0
> > > +
> > > +#endif
> > > +
> > >  static const struct acpi_device_id acpi_lpss_device_ids[] = {
> > >  	/* Generic LPSS devices */
> > > -	{ "INTL9C60", (unsigned long)&lpss_dma_desc },
> > > +	{ "INTL9C60", LPSS_PTR(lpss_dma_desc) },
> > >  
> > >  	/* Lynxpoint LPSS devices */
> > > -	{ "INT33C0", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT33C1", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT33C2", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT33C3", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT33C4", (unsigned long)&lpt_uart_dev_desc },
> > > -	{ "INT33C5", (unsigned long)&lpt_uart_dev_desc },
> > > -	{ "INT33C6", (unsigned long)&lpt_sdio_dev_desc },
> > > +	{ "INT33C0", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT33C1", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT33C2", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT33C3", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT33C4", LPSS_PTR(lpt_uart_dev_desc) },
> > > +	{ "INT33C5", LPSS_PTR(lpt_uart_dev_desc) },
> > > +	{ "INT33C6", LPSS_PTR(lpt_sdio_dev_desc) },
> > >  	{ "INT33C7", },
> > >  
> > >  	/* BayTrail LPSS devices */
> > > -	{ "80860F09", (unsigned long)&byt_pwm_dev_desc },
> > > -	{ "80860F0A", (unsigned long)&byt_uart_dev_desc },
> > > -	{ "80860F0E", (unsigned long)&byt_spi_dev_desc },
> > > -	{ "80860F14", (unsigned long)&byt_sdio_dev_desc },
> > > -	{ "80860F41", (unsigned long)&byt_i2c_dev_desc },
> > > +	{ "80860F09", LPSS_PTR(byt_pwm_dev_desc) },
> > > +	{ "80860F0A", LPSS_PTR(byt_uart_dev_desc) },
> > > +	{ "80860F0E", LPSS_PTR(byt_spi_dev_desc) },
> > > +	{ "80860F14", LPSS_PTR(byt_sdio_dev_desc) },
> > > +	{ "80860F41", LPSS_PTR(byt_i2c_dev_desc) },
> > >  	{ "INT33B2", },
> > >  
> > > -	{ "INT3430", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT3431", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT3432", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT3433", (unsigned long)&lpt_dev_desc },
> > > -	{ "INT3434", (unsigned long)&lpt_uart_dev_desc },
> > > -	{ "INT3435", (unsigned long)&lpt_uart_dev_desc },
> > > -	{ "INT3436", (unsigned long)&lpt_sdio_dev_desc },
> > > +	{ "INT3430", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT3431", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT3432", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT3433", LPSS_PTR(lpt_dev_desc) },
> > > +	{ "INT3434", LPSS_PTR(lpt_uart_dev_desc) },
> > > +	{ "INT3435", LPSS_PTR(lpt_uart_dev_desc) },
> > > +	{ "INT3436", LPSS_PTR(lpt_sdio_dev_desc) },
> > >  	{ "INT3437", },
> > >  
> > >  	{ }
> > >  };
> > >  
> > > +#ifdef CONFIG_X86_INTEL_LPSS
> > > +
> > >  static int is_memory(struct acpi_resource *res, void *not_used)
> > >  {
> > >  	struct resource r;
> > > @@ -511,10 +523,27 @@ static struct acpi_scan_handler lpss_handler = {
> > >  	.unbind = acpi_lpss_unbind,
> > >  };
> > >  
> > > +#endif /* CONFIG_X86_INTEL_LPSS */
> > > +
> > > +static int acpi_lpss_dummy_attach(struct acpi_device *adev,
> > > +				const struct acpi_device_id *id)
> > > +{
> > > +	return 1;
> > > +}
> > > +
> > > +static struct acpi_scan_handler lpss_dummy_handler = {
> > > +	.ids = acpi_lpss_device_ids,
> > > +	.attach = acpi_lpss_dummy_attach,
> > > +};
> > > +
> > >  void __init acpi_lpss_init(void)
> > >  {
> > > +#ifdef CONFIG_X86_INTEL_LPSS
> > >  	if (!lpt_clk_init()) {
> > >  		bus_register_notifier(&platform_bus_type, &acpi_lpss_nb);
> > >  		acpi_scan_add_handler(&lpss_handler);
> > > +		return;
> > >  	}
> > > +#endif
> > 
> > This whole #ifndef dance is ugly as hell. Can't we do any better?
> > 
> > > +	acpi_scan_add_handler(&lpss_dummy_handler);
> > 
> > Also I don't like these "dummy" things at all. Can't we make the code
> > work so that those are not needed?
> > 
> well, I'm not sure how to make it work w/o dummy handlers.
> Do you have any idea?
> 
> Oh, wait, as the .attach() callback for all the dummy handler just do
> one thing, aka, return 1 to attach the device, I think maybe we can have
> an acpi_scan_handler_dummy_attach() which does the same thing in
> drivers/acpi/scan.c, and invoke it for scan handlers w/o .attach().
> In this way, we do not need a dummy handler, but the #ifdef thing is
> still needed, to set/clear the .attach() callback.
> I will do a double check if this proposal sounds okay to you.

Yes it sounds ok to me.

I tried to figure out some way to get rid of the #ifdefs but couldn't
find any reasonable solution :-(
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