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:

quoted

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 <redacted>
---
  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.

quoted

+    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.

quoted

+
  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.