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Re: [PATCH 1/3] OMAP2+: UART: Remove cpu checks for populating errata flags



Hi Govindraj,

On 3/21/2012 5:24, Govindraj.R wrote:
From: "Govindraj.R"<govindraj.raja@xxxxxx>

Currently the errata is populated based on cpu checks this can
be removed and replaced with module version check of uart ip block.
MVR reg is provided within the uart reg map use the same
to populate the errata and thus now errata population and handling
can be managed within the driver itself.

Cc: Paul Walmsley<paul@xxxxxxxxx>
Cc: Kevin Hilman<khilman@xxxxxx>
Signed-off-by: Felipe Balbi<balbi@xxxxxx>
Signed-off-by: Govindraj.R<govindraj.raja@xxxxxx>
---
  arch/arm/mach-omap2/serial.c                  |    8 ---
  arch/arm/plat-omap/include/plat/omap-serial.h |    1 -
  drivers/tty/serial/omap-serial.c              |   62 ++++++++++++++++++++++++-
  3 files changed, 61 insertions(+), 10 deletions(-)

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index f590afc..330ee04 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -357,14 +357,6 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
  	omap_up.dma_rx_poll_rate = info->dma_rx_poll_rate;
  	omap_up.autosuspend_timeout = info->autosuspend_timeout;

-	/* Enable the MDR1 Errata i202 for OMAP2430/3xxx/44xx */
-	if (!cpu_is_omap2420()&&  !cpu_is_ti816x())
-		omap_up.errata |= UART_ERRATA_i202_MDR1_ACCESS;
-
-	/* Enable DMA Mode Force Idle Errata i291 for omap34xx/3630 */
-	if (cpu_is_omap34xx() || cpu_is_omap3630())
-		omap_up.errata |= UART_ERRATA_i291_DMA_FORCEIDLE;
-
  	pdata =&omap_up;
  	pdata_size = sizeof(struct omap_uart_port_info);

diff --git a/arch/arm/plat-omap/include/plat/omap-serial.h b/arch/arm/plat-omap/include/plat/omap-serial.h
index 9ff4444..1a52725 100644
--- a/arch/arm/plat-omap/include/plat/omap-serial.h
+++ b/arch/arm/plat-omap/include/plat/omap-serial.h
@@ -65,7 +65,6 @@ struct omap_uart_port_info {
  	bool			dma_enabled;	/* To specify DMA Mode */
  	unsigned int		uartclk;	/* UART clock rate */
  	upf_t			flags;		/* UPF_* flags */
-	u32			errata;
  	unsigned int		dma_rx_buf_size;
  	unsigned int		dma_rx_timeout;
  	unsigned int		autosuspend_timeout;
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index f809041..c7666d6 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -44,6 +44,13 @@
  #include<plat/dmtimer.h>
  #include<plat/omap-serial.h>

+#define UART_BUILD_REVISION(x, y)	(((x)<<  8) | (y))
+
+#define OMAP_UART_REV_42 0x0402
+#define OMAP_UART_REV_46 0x0406
+#define OMAP_UART_REV_52 0x0502
+#define OMAP_UART_REV_63 0x0603
+
  #define DEFAULT_CLK_SPEED 48000000 /* 48Mhz*/

  /* SCR register bitmasks */
@@ -1346,6 +1353,58 @@ static void uart_tx_dma_callback(int lch, u16 ch_status, void *data)
  	return;
  }

+static void omap_serial_fill_features_erratas(struct uart_omap_port *up)
+{
+	u32 mvr, scheme;
+	u16 revision, major, minor;
+
+	mvr = serial_in(up, UART_OMAP_MVER);
+
+	/* Check revision register scheme */
+	scheme = mvr&  (0x03<<  30);
+	scheme>>= 30;

Minor nit-pick, why not just ...

	scheme = mvr >> 30;

+	switch (scheme) {
+	case 0: /* Legacy Scheme: OMAP2/3 */
+		/* MINOR_REV[0:4], MAJOR_REV[4:7] */

Same scheme applies to OMAP1 devices too. So maybe we should include in the comment.

+		major = (mvr&  0xf0)>>  4;
+		minor = (mvr&  0x0f);
+		break;
+	case 1:
+		/* New Scheme: OMAP4+ */
+		/* MINOR_REV[0:5], MAJOR_REV[8:10] */
+		major = (mvr&  0x7<<  8)>>  8;

Nit-pick ...

	major = (mvr >> 8) & 0x7;

+		minor = (mvr&  0x3f);
+		break;
+	default:
+		dev_warn(&up->pdev->dev,
+			"Unknown %s revision, defaulting to highest\n",
+			up->name);
+		/* highest possible revision */
+		major = 0xff;
+		minor = 0xff;
+	}
+
+	/* normalize revision for the driver */
+	revision = UART_BUILD_REVISION(major, minor);
+
+	switch (revision) {
+	case OMAP_UART_REV_46:
+		up->errata |= (UART_ERRATA_i202_MDR1_ACCESS |
+				UART_ERRATA_i291_DMA_FORCEIDLE);
+		break;
+	case OMAP_UART_REV_52:
+		up->errata |= (UART_ERRATA_i202_MDR1_ACCESS |
+				UART_ERRATA_i291_DMA_FORCEIDLE);
+		break;
+	case OMAP_UART_REV_63:
+		up->errata |= UART_ERRATA_i202_MDR1_ACCESS;
+		break;
+	default:
+		break;
+	}

Should we also warn on an unknown revision?

+}
+
  static struct omap_uart_port_info *of_get_uart_port_info(struct device *dev)
  {
  	struct omap_uart_port_info *omap_up_info;
@@ -1443,7 +1502,6 @@ static int serial_omap_probe(struct platform_device *pdev)
  						"%d\n", DEFAULT_CLK_SPEED);
  	}
  	up->uart_dma.uart_base = mem->start;
-	up->errata = omap_up_info->errata;

  	if (omap_up_info->dma_enabled) {
  		up->uart_dma.uart_dma_tx = dma_tx->start;
@@ -1473,6 +1531,8 @@ static int serial_omap_probe(struct platform_device *pdev)
  	pm_runtime_enable(&pdev->dev);
  	pm_runtime_get_sync(&pdev->dev);

+	omap_serial_fill_features_erratas(up);
+
  	ui[up->port.line] = up;
  	serial_omap_add_console_port(up);

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