[PATCH] ACPI / LPSS: Remove non-existing clock control from Intel Lynxpoint I2C

[PATCH] ACPI / LPSS: Remove non-existing clock control from Intel Lynxpoint I2C

[Jarkko Nikula]

Intel Lynxpoint I2C does not have clock parameter register like SPI and UART
do have. Therefore remove LPSS_CLK_GATE flag from the Lynxpoint I2C device
description in order to not needlessly toggle clock enable bit in
non-existing register.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
For linux-next branch. This has been here since commit f58b082aed43
("ACPI / scan: Add special handler for Intel Lynxpoint LPSS devices")
without known problems.

Mika: I assumed this holds true for INT3432 and INT3433 too?
---
 drivers/acpi/acpi_lpss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 4f3febf8a589..9d43f79627a9 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -129,7 +129,7 @@ static struct lpss_device_desc lpt_dev_desc = {
 };
 
 static struct lpss_device_desc lpt_i2c_dev_desc = {
-	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR,
+	.flags = LPSS_CLK | LPSS_LTR,
 	.prv_offset = 0x800,
 };
 
-- 
2.1.4

Re: [PATCH] ACPI / LPSS: Remove non-existing clock control from Intel Lynxpoint I2C

[Mika Westerberg]

On Fri, Jan 23, 2015 at 09:42:39AM +0200, Jarkko Nikula wrote:
> Intel Lynxpoint I2C does not have clock parameter register like SPI and UART
> do have. Therefore remove LPSS_CLK_GATE flag from the Lynxpoint I2C device
> description in order to not needlessly toggle clock enable bit in
> non-existing register.
> 
> Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> ---
> For linux-next branch. This has been here since commit f58b082aed43
> ("ACPI / scan: Add special handler for Intel Lynxpoint LPSS devices")
> without known problems.
> 
> Mika: I assumed this holds true for INT3432 and INT3433 too?

Yes.

IIRC there used to be versions of Lynxpoint where the clock was actually
gated even if the document said the register is reserved. That's why the
I2C still tries to ungate the clock.

As long as you tested this properly,

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Re: [PATCH] ACPI / LPSS: Remove non-existing clock control from Intel Lynxpoint I2C

[Rafael J. Wysocki]

On Friday, January 23, 2015 12:52:39 PM Mika Westerberg wrote:
> On Fri, Jan 23, 2015 at 09:42:39AM +0200, Jarkko Nikula wrote:
> > Intel Lynxpoint I2C does not have clock parameter register like SPI and UART
> > do have. Therefore remove LPSS_CLK_GATE flag from the Lynxpoint I2C device
> > description in order to not needlessly toggle clock enable bit in
> > non-existing register.
> > 
> > Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> > ---
> > For linux-next branch. This has been here since commit f58b082aed43
> > ("ACPI / scan: Add special handler for Intel Lynxpoint LPSS devices")
> > without known problems.
> > 
> > Mika: I assumed this holds true for INT3432 and INT3433 too?
> 
> Yes.
> 
> IIRC there used to be versions of Lynxpoint where the clock was actually
> gated even if the document said the register is reserved. That's why the
> I2C still tries to ungate the clock.
> 
> As long as you tested this properly,
> 
> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Queued up for 3.20 then, thanks!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.