"Govindraj.R" <govindraj.raja@xxxxxx> writes:
> 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 | 79 ++++++++++++++++++++++++++++-------------
> 1 files changed, 54 insertions(+), 25 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
> index e1eba7f..55903f0 100644
> --- a/arch/arm/mach-omap2/serial.c
> +++ b/arch/arm/mach-omap2/serial.c
> @@ -63,6 +63,7 @@ struct omap_uart_state {
>
> 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 */
> @@ -87,6 +88,29 @@ static struct omap_device_pm_latency omap_uart_latency[] = {
> },
> };
>
> +static int console_uart_enable_hwmod(struct omap_device *od)
> +{
> + /* For early console we prevented hwmod reset and idle
> + * So before we enable the uart clocks idle and then
> + */
minor: fix multi-line comment style (search for multi-line in
Documentation/CodingStyle). Another one below.
Notice that you're moving existing code here, but also changing the
functionality without a description as to why. Based on the existing code:
You need a console_lock() here...
> + omap_hwmod_idle(od->hwmods[0]);
> + omap_hwmod_enable(od->hwmods[0]);
...and this should be omap_device_enable().
And you need a console_unlock() here.
Yes, you're subsequent patches avoid this problem, but we still need a real
fix other than checking for 'debug/loglevel', and when that happens,
we'll need a console lock here.
> + /* 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 = omap_uart_latency;
> +
> + return 0;
> +}
> +
> +static struct omap_device_pm_latency console_uart_latency[] = {
> + {
> + .activate_func = console_uart_enable_hwmod,
> + },
> +};
> +
> #ifdef CONFIG_PM
> static void omap_uart_enable_wakeup(struct platform_device *pdev, bool enable)
> {
> @@ -251,12 +275,20 @@ 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)
static inline
> +{
> + 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);
> @@ -271,18 +303,23 @@ 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;
> @@ -311,6 +348,7 @@ 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;
> @@ -357,6 +395,11 @@ 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);
> + od->pm_lats = console_uart_latency;
> + }
> +
> omap_device_disable_idle_on_suspend(pdev);
> oh->mux = omap_hwmod_mux_init(bdata->pads, bdata->pads_cnt);
>
> @@ -364,20 +407,6 @@ 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);
> }
Kevin
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