Re: [PATCH] ACPI / LPSS: Ignore 10ms delay for Braswell and Baytrail

["Kasagar, Srinidhi" <srinidhi.kasagar@intel.com>]

On Mon, Aug 24, 2015 at 12:44:55PM +0300, Mika Westerberg wrote:
> On Mon, Aug 24, 2015 at 10:39:21PM +0530, Kasagar, Srinidhi wrote:
> > Ok, then we have two options:
> > 
> > Let's drop LPSS_NO_D3_DELAY for BYT and duplicate the common devices which
> > are shared between Braswell and BYT & keep LPSS_NO_D3_DELAY only for BSW.
> 
> That sounds the safest option for now.
> 
> > OR
> > Use the cpu id to detect the platform which I believe not a good idea..
> > 
> > Because of few devices, I do not think it make sense to compromise on
> > the significant reduction in the resume delay.
> 
> I agree.

Refreshed the patch (below) affecting BSW platform alone.

But this does not solve your earlier concern on Broadwell which
shares the same acpi ids..

>From aa6861fee9e9ea4449c3c2da9292b1af1382d38f Mon Sep 17 00:00:00 2001
From: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
Date: Thu, 27 Aug 2015 19:58:32 +0530
Subject: [PATCH] ACPI / LPSS: Ignore 10ms delay for Braswell

LPSS devices in Braswell does not need the default 10ms
d3_delay imposed by PCI specification. Removing this
unnecessary delay significantly reduces the resume time
approximately upto 200ms on this platform.

Signed-off-by: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
---
 drivers/acpi/acpi_lpss.c |   78 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 64 insertions(+), 14 deletions(-)

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 46b58abb08c5..d3361d6e2e6e 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -60,6 +60,7 @@ ACPI_MODULE_NAME("acpi_lpss");
 #define LPSS_CLK_DIVIDER		BIT(2)
 #define LPSS_LTR			BIT(3)
 #define LPSS_SAVE_CTX			BIT(4)
+#define LPSS_NO_D3_DELAY		BIT(5)
 
 struct lpss_private_data;
 
@@ -134,11 +135,22 @@ static const struct lpss_device_desc lpt_dev_desc = {
 	.prv_offset = 0x800,
 };
 
+static const struct lpss_device_desc bsw_lpt_dev_desc = {
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
+			| LPSS_NO_D3_DELAY,
+	.prv_offset = 0x800,
+};
+
 static const struct lpss_device_desc lpt_i2c_dev_desc = {
 	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR,
 	.prv_offset = 0x800,
 };
 
+static const struct lpss_device_desc bsw_lpt_i2c_dev_desc = {
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR | LPSS_NO_D3_DELAY,
+	.prv_offset = 0x800,
+};
+
 static const struct lpss_device_desc lpt_uart_dev_desc = {
 	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR,
 	.clk_con_id = "baudclk",
@@ -146,16 +158,34 @@ static const struct lpss_device_desc lpt_uart_dev_desc = {
 	.setup = lpss_uart_setup,
 };
 
+static const struct lpss_device_desc bsw_lpt_uart_dev_desc = {
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
+			| LPSS_NO_D3_DELAY,
+	.clk_con_id = "baudclk",
+	.prv_offset = 0x800,
+	.setup = lpss_uart_setup,
+};
+
 static const struct lpss_device_desc lpt_sdio_dev_desc = {
 	.flags = LPSS_LTR,
 	.prv_offset = 0x1000,
 	.prv_size_override = 0x1018,
 };
 
+static const struct lpss_device_desc bsw_lpt_sdio_dev_desc = {
+	.flags = LPSS_LTR | LPSS_NO_D3_DELAY,
+	.prv_offset = 0x1000,
+	.prv_size_override = 0x1018,
+};
+
 static const struct lpss_device_desc byt_pwm_dev_desc = {
 	.flags = LPSS_SAVE_CTX,
 };
 
+static const struct lpss_device_desc bsw_pwm_dev_desc = {
+	.flags = LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
+};
+
 static const struct lpss_device_desc byt_uart_dev_desc = {
 	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
 	.clk_con_id = "baudclk",
@@ -178,8 +208,23 @@ static const struct lpss_device_desc byt_i2c_dev_desc = {
 	.setup = byt_i2c_setup,
 };
 
+static const struct lpss_device_desc bsw_i2c_dev_desc = {
+	.flags = LPSS_CLK | LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
+	.prv_offset = 0x800,
+	.setup = byt_i2c_setup,
+};
+
+static const struct lpss_device_desc bsw_uart_dev_desc = {
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
+			| LPSS_NO_D3_DELAY,
+	.clk_con_id = "baudclk",
+	.prv_offset = 0x800,
+	.setup = lpss_uart_setup,
+};
+
 static struct lpss_device_desc bsw_spi_dev_desc = {
-	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
+	.flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
+			| LPSS_NO_D3_DELAY,
 	.prv_offset = 0x400,
 	.setup = lpss_deassert_reset,
 };
@@ -214,18 +259,18 @@ static const struct acpi_device_id acpi_lpss_device_ids[] = {
 	{ "INT33FC", },
 
 	/* Braswell LPSS devices */
-	{ "80862288", LPSS_ADDR(byt_pwm_dev_desc) },
-	{ "8086228A", LPSS_ADDR(byt_uart_dev_desc) },
+	{ "80862288", LPSS_ADDR(bsw_pwm_dev_desc) },
+	{ "8086228A", LPSS_ADDR(bsw_uart_dev_desc) },
 	{ "8086228E", LPSS_ADDR(bsw_spi_dev_desc) },
-	{ "808622C1", LPSS_ADDR(byt_i2c_dev_desc) },
-
-	{ "INT3430", LPSS_ADDR(lpt_dev_desc) },
-	{ "INT3431", LPSS_ADDR(lpt_dev_desc) },
-	{ "INT3432", LPSS_ADDR(lpt_i2c_dev_desc) },
-	{ "INT3433", LPSS_ADDR(lpt_i2c_dev_desc) },
-	{ "INT3434", LPSS_ADDR(lpt_uart_dev_desc) },
-	{ "INT3435", LPSS_ADDR(lpt_uart_dev_desc) },
-	{ "INT3436", LPSS_ADDR(lpt_sdio_dev_desc) },
+	{ "808622C1", LPSS_ADDR(bsw_i2c_dev_desc) },
+
+	{ "INT3430", LPSS_ADDR(bsw_lpt_dev_desc) },
+	{ "INT3431", LPSS_ADDR(bsw_lpt_dev_desc) },
+	{ "INT3432", LPSS_ADDR(bsw_lpt_i2c_dev_desc) },
+	{ "INT3433", LPSS_ADDR(bsw_lpt_i2c_dev_desc) },
+	{ "INT3434", LPSS_ADDR(bsw_lpt_uart_dev_desc) },
+	{ "INT3435", LPSS_ADDR(bsw_lpt_uart_dev_desc) },
+	{ "INT3436", LPSS_ADDR(bsw_lpt_sdio_dev_desc) },
 	{ "INT3437", },
 
 	/* Wildcat Point LPSS devices */
@@ -558,9 +603,14 @@ static void acpi_lpss_restore_ctx(struct device *dev,
 	 * The following delay is needed or the subsequent write operations may
 	 * fail. The LPSS devices are actually PCI devices and the PCI spec
 	 * expects 10ms delay before the device can be accessed after D3 to D0
-	 * transition.
+	 * transition. However some platforms like BSW does not need this delay.
 	 */
-	msleep(10);
+	unsigned int delay = 10;	/* default 10ms delay */
+
+	if (pdata->dev_desc->flags & LPSS_NO_D3_DELAY)
+		delay = 0;
+
+	msleep(delay);
 
 	for (i = 0; i < LPSS_PRV_REG_COUNT; i++) {
 		unsigned long offset = i * sizeof(u32);
-- 
1.7.9.5