Re: [PATCH 2/3] OMAP3: PM: Conditional UART context save restore
"Reddy, Teerth" writes:
> From: Teerth Reddy
>
> Currently UART context save is done in idle thread thru a call
> to omap_uart_prepare_idle irrespective of what power state is
> attained by the power domain to which the UART belongs to. This
> patch allows omap_uart_prepare_idle to take power state as a
> parameter and this function in turn does a uart context save
> only if the passed power state is PWRDM_POWER_OFF. In the restore
> path a restore will happen only if a valid save has happened.
>
> Signed-off-by: Thara Gopinath
> Signed-off-by: Teerth Reddy
The idea is fine, but the implementation is not quite right. Some
comments on that below.
I like this as it also removes the dependency on enable_off_mode.
That being said, I'd rather not spend much more time hacking on this
layer. Soon, we will have the new omap-serial driver, and we will be
moving most of this PM smarts into the the omap-serial driver itself
using runtime PM.
> ---
> arch/arm/mach-omap2/pm34xx.c |6 +++---
> arch/arm/mach-omap2/serial.c | 26 --
> arch/arm/plat-omap/include/plat/serial.h |2 +-
> 3 files changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 207905d..85a21e7 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -418,7 +418,7 @@ void omap_sram_idle(void)
> } else
> omap3_per_save_context();
> }
> - omap_uart_prepare_idle(2);
> + omap_uart_prepare_idle(2, per_next_state);
> }
>
> if (pwrdm_read_pwrst(cam_pwrdm) == PWRDM_POWER_ON)
> @@ -426,8 +426,8 @@ void omap_sram_idle(void)
>
> /* CORE */
> if (core_next_state < PWRDM_POWER_ON) {
> - omap_uart_prepare_idle(0);
> - omap_uart_prepare_idle(1);
> + omap_uart_prepare_idle(0, core_next_state);
> + omap_uart_prepare_idle(1, core_next_state);
> if (core_next_state == PWRDM_POWER_OFF) {
> omap3_core_save_context();
> omap3_prcm_save_context();
> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
> index d545eed..85e09ef 100644
> --- a/arch/arm/mach-omap2/serial.c
> +++ b/arch/arm/mach-omap2/serial.c
> @@ -185,9 +185,6 @@ static void omap_uart_save_context(struct omap_uart_state
> *uart)
> u16 lcr = 0;
> struct plat_serial8250_port *p = uart->p;
>
> - if (!enable_off_mode)
> - return;
> -
> lcr = serial_read_reg(p, UART_LCR);
> serial_write_reg(p, UART_LCR, 0xBF);
> uart->dll = serial_read_reg(p, UART_DLL);
> @@ -206,9 +203,6 @@ static void omap_uart_restore_context(struct
> omap_uart_state *uart)
> u16 efr = 0;
> struct plat_serial8250_port *p = uart->p;
>
> - if (!enable_off_mode)
> - return;
> -
> if (!uart->context_valid)
> return;
>
> @@ -252,12 +246,24 @@ static inline void omap_uart_enable_clocks(struct
> omap_uart_state *uart)
>
> #ifdef CONFIG_PM
>
> -static inline void omap_uart_disable_clocks(struct omap_uart_state *uart)
> +static inline void omap_uart_disable_clocks(struct omap_uart_state *uart,
> + int power_state)
> {
> if (!uart->clocked)
> return;
>
> - omap_uart_save_context(uart);
> + if (power_state == PWRDM_POWER_OFF) {
> + if (uart->context_valid)
> + return;
This check is done inside save_context
> + if (!uart->clocked) {
> + clk_enable(uart->ick);
> + clk_enable(uart->fck);
> + }
What is this for? The first statement above checks for !uart->clocked
and returns, so this should never happen.
> + omap_uart_save_context(uart);
> + } else if (!uart->clocked) {
> + return;
This else clause isn't needed. It's already checked above.
> + }
> +
> uart->clocked = 0;
> clk_disable(uart->ick);
> clk_disable(uart->fck);
> @@ -347,13 +353,13 @@ static void omap_uart_idle_timer(unsigned long data)
> omap_uart_allow_sleep(uart);
> }
>
> -void omap_uart_prepare_idle(int num)
> +void omap_uart_prepare_idle(int num, int power_state)
> {
> struct omap_uart_state *uart;
>
> list_for_each_entry(uart, &uart_list, node) {
> if (num == uart->num && uart->can_sleep) {
> - omap_uart_disable_clocks(uart);
> + omap_uart_disable_clocks(uart, power_state);
> return;
> }
> }
> diff --git a/arch/arm/plat-omap/include/plat/serial.h
> b/arch/arm/plat-omap/include/plat/serial.h
> index 19145f5..71ca2da 100644
> --- a/arch/arm/plat-omap/include/plat/serial.h
> +++ b/arch/arm/plat-omap/include/plat/serial.h
> @@ -99,7 +99,7 @@
[PATCH 2/3] OMAP3: PM: Conditional UART context save restore
From: Teerth Reddy
Currently UART context save is done in idle thread thru a call
to omap_uart_prepare_idle irrespective of what power state is
attained by the power domain to which the UART belongs to. This
patch allows omap_uart_prepare_idle to take power state as a
parameter and this function in turn does a uart context save
only if the passed power state is PWRDM_POWER_OFF. In the restore
path a restore will happen only if a valid save has happened.
Signed-off-by: Thara Gopinath
Signed-off-by: Teerth Reddy
---
arch/arm/mach-omap2/pm34xx.c |6 +++---
arch/arm/mach-omap2/serial.c | 26 --
arch/arm/plat-omap/include/plat/serial.h |2 +-
3 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 207905d..85a21e7 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -418,7 +418,7 @@ void omap_sram_idle(void)
} else
omap3_per_save_context();
}
- omap_uart_prepare_idle(2);
+ omap_uart_prepare_idle(2, per_next_state);
}
if (pwrdm_read_pwrst(cam_pwrdm) == PWRDM_POWER_ON)
@@ -426,8 +426,8 @@ void omap_sram_idle(void)
/* CORE */
if (core_next_state < PWRDM_POWER_ON) {
- omap_uart_prepare_idle(0);
- omap_uart_prepare_idle(1);
+ omap_uart_prepare_idle(0, core_next_state);
+ omap_uart_prepare_idle(1, core_next_state);
if (core_next_state == PWRDM_POWER_OFF) {
omap3_core_save_context();
omap3_prcm_save_context();
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index d545eed..85e09ef 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -185,9 +185,6 @@ static void omap_uart_save_context(struct omap_uart_state
*uart)
u16 lcr = 0;
struct plat_serial8250_port *p = uart->p;
- if (!enable_off_mode)
- return;
-
lcr = serial_read_reg(p, UART_LCR);
serial_write_reg(p, UART_LCR, 0xBF);
uart->dll = serial_read_reg(p, UART_DLL);
@@ -206,9 +203,6 @@ static void omap_uart_restore_context(struct
omap_uart_state *uart)
u16 efr = 0;
struct plat_serial8250_port *p = uart->p;
- if (!enable_off_mode)
- return;
-
if (!uart->context_valid)
return;
@@ -252,12 +246,24 @@ static inline void omap_uart_enable_clocks(struct
omap_uart_state *uart)
#ifdef CONFIG_PM
-static inline void omap_uart_disable_clocks(struct omap_uart_state *uart)
+static inline void omap_uart_disable_clocks(struct omap_uart_state *uart,
+ int power_state)
{
if (!uart->clocked)
return;
- omap_uart_save_context(uart);
+ if (power_state == PWRDM_POWER_OFF) {
+ if (uart->context_valid)
+ return;
+ if (!uart->clocked) {
+ clk_enable(uart->ick);
+ clk_enable(uart->fck);
+ }
+ omap_uart_save_context(uart);
+ } else if (!uart->clocked) {
+ return;
+ }
+
uart->clocked = 0;
clk_disable(uart->ick);
clk_disable(uart->fck);
@@ -347,13 +353,13 @@ static void omap_uart_idle_timer(unsigned long data)
omap_uart_allow_sleep(uart);
}
-void omap_uart_prepare_idle(int num)
+void omap_uart_prepare_idle(int num, int power_state)
{
struct omap_uart_state *uart;
list_for_each_entry(uart, &uart_list, node) {
if (num == uart->num && uart->can_sleep) {
- omap_uart_disable_clocks(uart);
+ omap_uart_disable_clocks(uart, power_state);
return;
}
}
diff --git a/arch/arm/plat-omap/include/plat/serial.h
b/arch/arm/plat-omap/include/plat/serial.h
index 19145f5..71ca2da 100644
--- a/arch/arm/plat-omap/include/plat/serial.h
+++ b/arch/arm/plat-omap/include/plat/serial.h
@@ -99,7 +99,7 @@ extern void omap_serial_init_port(int port);
extern int omap_uart_can_sleep(void);
extern void omap_uart_check_wakeup(void);
extern void omap_uart_prepare_suspend(void);
-extern void omap_uart_prepare_idle(int num);
+extern void omap_uart_prepare_idle(int num, int power_state);
extern void omap_uart_resume_idle(int num);
extern void omap_uart_enable_irqs(int enable);
#endif
--
1.5.4.3
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