Omap-uart can be used as console uart to print early boot
messages using earlyprintk so for console uart prevent
hwmod reset or idling during bootup.
Identify the console_uart set the id and use the custom
pm_latency ops for console uart for the first time
to idle console uart left enabled from bootup and then enable
them back and reset pm_latency ops to default ops.
Thanks to Kevin Hilman <khilman@xxxxxx> for suggesting
this approach.
Signed-off-by: Govindraj.R <govindraj.raja@xxxxxx>
---
arch/arm/mach-omap2/serial.c | 86 +++++++++++++++++++++++++++++------------
1 files changed, 61 insertions(+), 25 deletions(-)
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 4d65d00..631d72a 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -61,8 +61,10 @@ struct omap_uart_state {
struct platform_device *pdev;
};
+static struct omap_device_pm_latency *default_uart_latency;
static LIST_HEAD(uart_list);
static u8 num_uarts;
+static u8 console_uart_id = -1;
#define DEFAULT_RXDMA_POLLRATE 1 /* RX DMA polling rate (us) */
#define DEFAULT_RXDMA_BUFSIZE 4096 /* RX DMA buffer size */
@@ -78,6 +80,34 @@ static struct omap_uart_port_info omap_serial_default_info[] __initdata = {
},
};
+static int console_uart_enable_hwmod(struct omap_device *od)
+{
+ console_lock();
+ /*
+ * For early console we prevented hwmod reset and idle
+ * So before we enable the uart clocks idle the console
+ * uart clocks, then enable back the console uart hwmod.
+ */
+ omap_hwmod_idle(od->hwmods[0]);
+ omap_hwmod_enable(od->hwmods[0]);
+ console_unlock();
+
+ /*
+ * Restore the default activate/deactivate funcs,
+ * since now we have set the hwmod state machine right
+ * with the idle/enable for console uart
+ */
+ od->pm_lats = default_uart_latency;
+
+ return 0;
+}
+
+static struct omap_device_pm_latency console_uart_latency[] = {
+ {
+ .activate_func = console_uart_enable_hwmod,
+ },
+};
+
#ifdef CONFIG_PM
int omap_uart_can_sleep(void)
@@ -264,12 +294,20 @@ static void omap_serial_fill_default_pads(struct omap_board_data *bdata)
static void omap_serial_fill_default_pads(struct omap_board_data *bdata) {}
#endif
+char *cmdline_find_option(char *str)
+{
+ extern char *saved_command_line;
+
+ return strstr(saved_command_line, str);
+}
+
static int __init omap_serial_early_init(void)
{
do {
char oh_name[MAX_UART_HWMOD_NAME_LEN];
struct omap_hwmod *oh;
struct omap_uart_state *uart;
+ char uart_name[MAX_UART_HWMOD_NAME_LEN];
snprintf(oh_name, MAX_UART_HWMOD_NAME_LEN,
"uart%d", num_uarts + 1);
@@ -284,18 +322,23 @@ static int __init omap_serial_early_init(void)
uart->oh = oh;
uart->num = num_uarts++;
list_add_tail(&uart->node, &uart_list);
+ snprintf(uart_name, MAX_UART_HWMOD_NAME_LEN,
+ "%s%d", OMAP_SERIAL_NAME, uart->num);
+
+ if (cmdline_find_option(uart_name)) {
+ console_uart_id = uart->num;
+ /*
+ * omap-uart can be used for earlyprintk logs
+ * So if omap-uart is used as console then prevent
+ * uart reset and idle to get logs from omap-uart
+ * until uart console driver is available to take
+ * care for console messages.
+ * Idling or resetting omap-uart while printing logs
+ * early boot logs can stall the boot-up.
+ */
+ oh->flags |= HWMOD_INIT_NO_IDLE | HWMOD_INIT_NO_RESET;
+ }
- /*
- * NOTE: omap_hwmod_setup*() has not yet been called,
- * so no hwmod functions will work yet.
- */
-
- /*
- * During UART early init, device need to be probed
- * to determine SoC specific init before omap_device
- * is ready. Therefore, don't allow idle here
- */
- uart->oh->flags |= HWMOD_INIT_NO_IDLE | HWMOD_INIT_NO_RESET;
} while (1);
return 0;
@@ -324,6 +367,7 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
u32 pdata_size = 0;
char *name;
struct omap_uart_port_info omap_up;
+ struct omap_device *od;
if (WARN_ON(!bdata))
return;
@@ -369,6 +413,12 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
WARN(IS_ERR(pdev), "Could not build omap_device for %s: %s.\n",
name, oh->name);
+ if (console_uart_id == bdata->id) {
+ od = to_omap_device(pdev);
+ default_uart_latency = od->pm_lats;
+ od->pm_lats = console_uart_latency;
+ }
+
omap_device_disable_idle_on_suspend(pdev);
oh->mux = omap_hwmod_mux_init(bdata->pads, bdata->pads_cnt);
@@ -376,20 +426,6 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
oh->dev_attr = uart;
- console_lock(); /* in case the earlycon is on the UART */
-
- /*
- * Because of early UART probing, UART did not get idled
- * on init. Now that omap_device is ready, ensure full idle
- * before doing omap_device_enable().
- */
- omap_hwmod_idle(uart->oh);
-
- omap_device_enable(uart->pdev);
- omap_device_idle(uart->pdev);
-
- console_unlock();
-
if ((cpu_is_omap34xx() || cpu_is_omap44xx()) && bdata->pads)
device_init_wakeup(&pdev->dev, true);
}
--
1.7.4.1
--
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