Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1576200 > unrolled thread

[PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon Christopher Covington <cov@codeaurora.org> - 2017-02-08 02:00 +0100
    Re: [PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon Timur Tabi <timur@codeaurora.org> - 2017-02-08 05:10 +0100
      Re: [PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon Shanker Donthineni <shankerd@codeaurora.org> - 2017-02-08 05:50 +0100

#1576200 — [PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon

The previous change worked around QDF2432v1 and QDF2400v1 SoC erratum 44
for the full-fledged console, when UART AMBA Port (UAP) data is available.
Additionally provide a workaround the earlycon case, again checking TXFE ==
0 instead of BUSY == 1. As earlycon is operating before UAP data is
available, the implementation is different than in the preceding patch.

Signed-off-by: Christopher Covington <cov@codeaurora.org>
---
 drivers/tty/serial/amba-pl011.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 41e51901d6ef..f25e7c994f8e 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2411,6 +2411,29 @@ static bool qdf2400_e44(void) {
 	    cpu_var_model == MIDR_QCOM_FALKOR_V1);
 }
 
+#ifdef CONFIG_QCOM_QDF2400_ERRATUM_44
+static void qdf2400_e44_putc(struct uart_port *port, int c)
+{
+	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
+		cpu_relax();
+	if (port->iotype == UPIO_MEM32)
+		writel(c, port->membase + UART01x_DR);
+	else
+		writeb(c, port->membase + UART01x_DR);
+	while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE))
+		cpu_relax();
+}
+
+static void qdf2400_e44_early_write(struct console *con, const char *s, unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, qdf2400_e44_putc);
+}
+#else
+#define qdf2400_e44_early_write pl011_early_write
+#endif
+
 static void pl011_putc(struct uart_port *port, int c)
 {
 	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
@@ -2436,7 +2459,10 @@ static int __init pl011_early_console_setup(struct earlycon_device *device,
 	if (!device->port.membase)
 		return -ENODEV;
 
-	device->con->write = pl011_early_write;
+	if (qdf2400_e44())
+		device->con->write = qdf2400_e44_early_write;
+	else
+		device->con->write = pl011_early_write;
 	return 0;
 }
 OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);
-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora
Forum, a Linux Foundation Collaborative Project.

[toc] | [next] | [standalone]

#1576268

Christopher Covington wrote:
> The previous change worked around QDF2432v1 and QDF2400v1 SoC erratum 44
> for the full-fledged console, when UART AMBA Port (UAP) data is available.
> Additionally provide a workaround the earlycon case, again checking TXFE ==
> 0 instead of BUSY == 1. As earlycon is operating before UAP data is
> available, the implementation is different than in the preceding patch.
>
> Signed-off-by: Christopher Covington <cov@codeaurora.org>
> ---
>   drivers/tty/serial/amba-pl011.c | 28 +++++++++++++++++++++++++++-
>   1 file changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 41e51901d6ef..f25e7c994f8e 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2411,6 +2411,29 @@ static bool qdf2400_e44(void) {
>   	    cpu_var_model == MIDR_QCOM_FALKOR_V1);
>   }
>   
> +#ifdef CONFIG_QCOM_QDF2400_ERRATUM_44
> +static void qdf2400_e44_putc(struct uart_port *port, int c)
> +{
> +	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> +		cpu_relax();
> +	if (port->iotype == UPIO_MEM32)
> +		writel(c, port->membase + UART01x_DR);
> +	else
> +		writeb(c, port->membase + UART01x_DR);
I believe 32-bit writes are safe on QDF2400v1, so I think you technically don't 
need the UPIO_MEM32 check.  Just always call writel.
> +	while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE))
> +		cpu_relax();
> +}
> +
> +static void qdf2400_e44_early_write(struct console *con, const char *s, unsigned n)
> +{
> +	struct earlycon_device *dev = con->data;
> +
> +	uart_console_write(&dev->port, s, n, qdf2400_e44_putc);
> +}
> +#else
> +#define qdf2400_e44_early_write pl011_early_write
> +#endif
Same with patch 1/2.  If you change qdf2400_e44(), you don't need the #else block.
> +
>   static void pl011_putc(struct uart_port *port, int c)
>   {
>   	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> @@ -2436,7 +2459,10 @@ static int __init pl011_early_console_setup(struct earlycon_device *device,
>   	if (!device->port.membase)
>   		return -ENODEV;
>   
> -	device->con->write = pl011_early_write;
> +	if (qdf2400_e44())
> +		device->con->write = qdf2400_e44_early_write;
> +	else
> +		device->con->write = pl011_early_write;
>   	return 0;
>   }
>   OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);


-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
Code Aurora Forum, hosted by The Linux Foundation.

[toc] | [prev] | [next] | [standalone]

#1576275

Hi Cov,

The same PL011 driver will be used in virtutal machine, make sure your 
changes have no side effects in VM.



On 02/07/2017 10:07 PM, Timur Tabi wrote:
> Christopher Covington wrote:
>> The previous change worked around QDF2432v1 and QDF2400v1 SoC erratum 44
>> for the full-fledged console, when UART AMBA Port (UAP) data is 
>> available.
>> Additionally provide a workaround the earlycon case, again checking 
>> TXFE ==
>> 0 instead of BUSY == 1. As earlycon is operating before UAP data is
>> available, the implementation is different than in the preceding patch.
>>
>> Signed-off-by: Christopher Covington <cov@codeaurora.org>
>> ---
>>   drivers/tty/serial/amba-pl011.c | 28 +++++++++++++++++++++++++++-
>>   1 file changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/amba-pl011.c 
>> b/drivers/tty/serial/amba-pl011.c
>> index 41e51901d6ef..f25e7c994f8e 100644
>> --- a/drivers/tty/serial/amba-pl011.c
>> +++ b/drivers/tty/serial/amba-pl011.c
>> @@ -2411,6 +2411,29 @@ static bool qdf2400_e44(void) {
>>           cpu_var_model == MIDR_QCOM_FALKOR_V1);
>>   }
>>   +#ifdef CONFIG_QCOM_QDF2400_ERRATUM_44
>> +static void qdf2400_e44_putc(struct uart_port *port, int c)
>> +{
>> +    while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
>> +        cpu_relax();
>> +    if (port->iotype == UPIO_MEM32)
>> +        writel(c, port->membase + UART01x_DR);
>> +    else
>> +        writeb(c, port->membase + UART01x_DR);
> I believe 32-bit writes are safe on QDF2400v1, so I think you 
> technically don't need the UPIO_MEM32 check.  Just always call writel.
>> +    while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE))
>> +        cpu_relax();
>> +}
>> +
>> +static void qdf2400_e44_early_write(struct console *con, const char 
>> *s, unsigned n)
>> +{
>> +    struct earlycon_device *dev = con->data;
>> +
>> +    uart_console_write(&dev->port, s, n, qdf2400_e44_putc);
>> +}
>> +#else
>> +#define qdf2400_e44_early_write pl011_early_write
>> +#endif
> Same with patch 1/2.  If you change qdf2400_e44(), you don't need the 
> #else block.
>> +
>>   static void pl011_putc(struct uart_port *port, int c)
>>   {
>>       while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
>> @@ -2436,7 +2459,10 @@ static int __init 
>> pl011_early_console_setup(struct earlycon_device *device,
>>       if (!device->port.membase)
>>           return -ENODEV;
>>   -    device->con->write = pl011_early_write;
>> +    if (qdf2400_e44())
>> +        device->con->write = qdf2400_e44_early_write;
>> +    else
>> +        device->con->write = pl011_early_write;
>>       return 0;
>>   }
>>   OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);
>
>

-- 
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web