This patch can be ignored. The RX fifo clear logic did not really work for low C states (C1 / C2) and you would still get garbage. I'll send an updated patch where I have replaced the logic by an ignore timer for the first millisecond after clocks are enabled. Also, I forgot v2 out from this. >-----Original Message----- >From: linux-omap-owner@xxxxxxxxxxxxxxx >[mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Kristo >Tero (Nokia-D/Tampere) >Sent: 10 February, 2010 18:29 >To: linux-omap@xxxxxxxxxxxxxxx >Subject: [PATCH] OMAP3: Serial: Improved sleep logic > >From: Tero Kristo <tero.kristo@xxxxxxxxx> > >This patch contains following improvements: >- Only RX interrupt will now kick the sleep prevent timer >- TX fifo status is checked before disabling clocks, this will prevent > on-going transmission to be cut >- Smartidle is disabled while entering idle if we have data in >the transmit > buffer because having this enabled would prevent wakeups from the TX > interrupt and this would cause pauses while sending large >blocks of data >- Sleep prevent timer is changed to use ktime_get() instead of >a jiffy timer > as jiffy timers are not valid within idle loop (tick >scheduler is stopped) >- RX and TX fifos are cleared when clocks are enabled, this >will purge the > first character from RX fifo, which is most likely garbage > >Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxx> >--- > arch/arm/mach-omap2/serial.c | 70 >+++++++++++++++++++++++++++--------------- > 1 files changed, 45 insertions(+), 25 deletions(-) > >diff --git a/arch/arm/mach-omap2/serial.c >b/arch/arm/mach-omap2/serial.c >index 837b347..d7d96ba 100644 >--- a/arch/arm/mach-omap2/serial.c >+++ b/arch/arm/mach-omap2/serial.c >@@ -23,12 +23,15 @@ > #include <linux/serial_reg.h> > #include <linux/clk.h> > #include <linux/io.h> >+#include <linux/delay.h> > > #include <plat/common.h> > #include <plat/board.h> > #include <plat/clock.h> > #include <plat/control.h> > >+#include <asm/div64.h> >+ > #include "prm.h" > #include "pm.h" > #include "prm-regbits-34xx.h" >@@ -36,13 +39,13 @@ > #define UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV 0x52 > #define UART_OMAP_WER 0x17 /* Wake-up enable register */ > >-#define DEFAULT_TIMEOUT (5 * HZ) >+#define DEFAULT_TIMEOUT (5LL * NSEC_PER_SEC) > > struct omap_uart_state { > int num; > int can_sleep; >- struct timer_list timer; >- u32 timeout; >+ ktime_t expire_time; >+ u64 timeout; > > void __iomem *wk_st; > void __iomem *wk_en; >@@ -231,6 +234,9 @@ static inline void >omap_uart_enable_clocks(struct omap_uart_state *uart) > clk_enable(uart->fck); > uart->clocked = 1; > omap_uart_restore_context(uart); >+ >+ /* Clear RX and TX fifos, as they contain garbage at >this point */ >+ serial_write_reg(uart->p, UART_FCR, 0xa7); > } > > #ifdef CONFIG_PM >@@ -302,9 +308,7 @@ static void omap_uart_block_sleep(struct >omap_uart_state *uart) > omap_uart_smart_idle_enable(uart, 0); > uart->can_sleep = 0; > if (uart->timeout) >- mod_timer(&uart->timer, jiffies + uart->timeout); >- else >- del_timer(&uart->timer); >+ uart->expire_time = ktime_add_ns(ktime_get(), >uart->timeout); > } > > static void omap_uart_allow_sleep(struct omap_uart_state *uart) >@@ -317,25 +321,28 @@ static void omap_uart_allow_sleep(struct >omap_uart_state *uart) > if (!uart->clocked) > return; > >- omap_uart_smart_idle_enable(uart, 1); >+ if (serial_read_reg(uart->p, UART_LSR) & UART_LSR_TEMT) >+ omap_uart_smart_idle_enable(uart, 1); > uart->can_sleep = 1; >- del_timer(&uart->timer); >-} >- >-static void omap_uart_idle_timer(unsigned long data) >-{ >- struct omap_uart_state *uart = (struct omap_uart_state *)data; >- >- omap_uart_allow_sleep(uart); > } > > void omap_uart_prepare_idle(int num) > { > struct omap_uart_state *uart; >+ ktime_t t; > > list_for_each_entry(uart, &uart_list, node) { >+ if (num == uart->num && !uart->can_sleep) { >+ t = ktime_get(); >+ if (t.tv64 > uart->expire_time.tv64) >+ uart->can_sleep = 1; >+ } > if (num == uart->num && uart->can_sleep) { >- omap_uart_disable_clocks(uart); >+ if (serial_read_reg(uart->p, UART_LSR) & >+ UART_LSR_TEMT) >+ omap_uart_disable_clocks(uart); >+ else >+ omap_uart_smart_idle_enable(uart, 0); > return; > } > } >@@ -360,6 +367,7 @@ void omap_uart_resume_idle(int num) > /* Check for normal UART wakeup */ > if (__raw_readl(uart->wk_st) & uart->wk_mask) > omap_uart_block_sleep(uart); >+ > return; > } > } >@@ -407,8 +415,14 @@ int omap_uart_can_sleep(void) > static irqreturn_t omap_uart_interrupt(int irq, void *dev_id) > { > struct omap_uart_state *uart = dev_id; >+ u8 lsr; > >- omap_uart_block_sleep(uart); >+ lsr = serial_read_reg(uart->p, UART_LSR); >+ /* Check for receive interrupt */ >+ if (lsr & UART_LSR_DR) >+ omap_uart_block_sleep(uart); >+ if (lsr & UART_LSR_TEMT && uart->can_sleep) >+ omap_uart_smart_idle_enable(uart, 1); > > return IRQ_NONE; > } >@@ -420,9 +434,9 @@ static void omap_uart_idle_init(struct >omap_uart_state *uart) > > uart->can_sleep = 0; > uart->timeout = DEFAULT_TIMEOUT; >- setup_timer(&uart->timer, omap_uart_idle_timer, >- (unsigned long) uart); >- mod_timer(&uart->timer, jiffies + uart->timeout); >+ >+ uart->expire_time = ktime_add_ns(ktime_get(), uart->timeout); >+ > omap_uart_smart_idle_enable(uart, 0); > > if (cpu_is_omap34xx()) { >@@ -505,8 +519,12 @@ static ssize_t sleep_timeout_show(struct >device *dev, > struct platform_device, dev); > struct omap_uart_state *uart = container_of(pdev, > struct omap_uart_state, pdev); >+ u64 val; > >- return sprintf(buf, "%u\n", uart->timeout / HZ); >+ val = uart->timeout; >+ >+ do_div(val, NSEC_PER_SEC); >+ return sprintf(buf, "%llu\n", val); > } > > static ssize_t sleep_timeout_store(struct device *dev, >@@ -524,10 +542,12 @@ static ssize_t >sleep_timeout_store(struct device *dev, > return -EINVAL; > } > >- uart->timeout = value * HZ; >- if (uart->timeout) >- mod_timer(&uart->timer, jiffies + uart->timeout); >- else >+ uart->timeout = (u64)value * NSEC_PER_SEC; >+ if (uart->timeout) { >+ uart->expire_time = ktime_get(); >+ uart->expire_time = >+ ktime_add_ns(uart->expire_time, uart->timeout); >+ } else > /* A zero value means disable timeout feature */ > omap_uart_block_sleep(uart); > >-- >1.5.4.3 > >-- >To unsubscribe from this list: send the line "unsubscribe >linux-omap" in >the body of a message to majordomo@xxxxxxxxxxxxxxx >More majordomo info at http://vger.kernel.org/majordomo-info.html >-- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
