Re: [RFC 1/5] [media] rc: update sunxi-ir driver to get base frequency from devicetree

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Hey Mauro,

Thanks for your fast feedback!

I will rework the driver like you suggested it.

Does somebody have any concerns about the Devicetree property (base-clk-frequency = < frequency >;)?


Regards,
Philipp

On 16.12.2017 10:18, Mauro Carvalho Chehab wrote:
Em Sat, 16 Dec 2017 03:49:10 +0100
Philipp Rossak <embed3d@xxxxxxxxx> escreveu:

Hi Phillip,

This is not a full review of this patchset. I just want to point you
that you should keep supporting existing DT files.

This patch updates the sunxi-ir driver to set the ir base clock from
devicetree.

This is neccessary since there are different ir recievers on the
market, that operate with different frequencys. So this value needs to
be set depending on the attached receiver.

Please don't break backward compatibility with old DT files. In this
specific case, it seems simple enough to be backward-compatible.


Signed-off-by: Philipp Rossak <embed3d@xxxxxxxxx>
---
  drivers/media/rc/sunxi-cir.c | 20 +++++++++++---------
  1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/media/rc/sunxi-cir.c b/drivers/media/rc/sunxi-cir.c
index 97f367b446c4..55b53d6463e9 100644
--- a/drivers/media/rc/sunxi-cir.c
+++ b/drivers/media/rc/sunxi-cir.c
@@ -72,12 +72,6 @@
  /* CIR_REG register idle threshold */
  #define REG_CIR_ITHR(val)    (((val) << 8) & (GENMASK(15, 8)))
-/* Required frequency for IR0 or IR1 clock in CIR mode */
-#define SUNXI_IR_BASE_CLK     8000000
-/* Frequency after IR internal divider  */
-#define SUNXI_IR_CLK          (SUNXI_IR_BASE_CLK / 64)

Keep those to definitions...

-/* Sample period in ns */
-#define SUNXI_IR_SAMPLE       (1000000000ul / SUNXI_IR_CLK)
  /* Noise threshold in samples  */
  #define SUNXI_IR_RXNOISE      1
  /* Idle Threshold in samples */
@@ -122,7 +116,7 @@ static irqreturn_t sunxi_ir_irq(int irqno, void *dev_id)
  			/* for each bit in fifo */
  			dt = readb(ir->base + SUNXI_IR_RXFIFO_REG);
  			rawir.pulse = (dt & 0x80) != 0;
-			rawir.duration = ((dt & 0x7f) + 1) * SUNXI_IR_SAMPLE;
+			rawir.duration = ((dt & 0x7f) + 1) * ir->rc->rx_resolution;
  			ir_raw_event_store_with_filter(ir->rc, &rawir);
  		}
  	}
@@ -148,6 +142,7 @@ static int sunxi_ir_probe(struct platform_device *pdev)
  	struct device_node *dn = dev->of_node;
  	struct resource *res;
  	struct sunxi_ir *ir;
+	u32 b_clk_freq;
ir = devm_kzalloc(dev, sizeof(struct sunxi_ir), GFP_KERNEL);
  	if (!ir)
@@ -172,6 +167,12 @@ static int sunxi_ir_probe(struct platform_device *pdev)
  		return PTR_ERR(ir->clk);
  	}
+ /* Required frequency for IR0 or IR1 clock in CIR mode */
+	if (of_property_read_u32(dn, "base-clk-frequency", &b_clk_freq)) {
+		dev_err(dev, "failed to get ir base clock frequency.\n");
+		return -ENODATA;
+	}
+

And here, instead of returning an error, if the property can't be read,
it means it is an older DT file. Just default to SUNXI_IR_BASE_CLK.
This will make it backward-compatible with old DT files that don't have
such property.

Regards,
Mauro


  	/* Reset (optional) */
  	ir->rst = devm_reset_control_get_optional_exclusive(dev, NULL);
  	if (IS_ERR(ir->rst))
@@ -180,7 +181,7 @@ static int sunxi_ir_probe(struct platform_device *pdev)
  	if (ret)
  		return ret;
- ret = clk_set_rate(ir->clk, SUNXI_IR_BASE_CLK);
+	ret = clk_set_rate(ir->clk, b_clk_freq);
  	if (ret) {
  		dev_err(dev, "set ir base clock failed!\n");
  		goto exit_reset_assert;
@@ -225,7 +226,8 @@ static int sunxi_ir_probe(struct platform_device *pdev)
  	ir->rc->map_name = ir->map_name ?: RC_MAP_EMPTY;
  	ir->rc->dev.parent = dev;
  	ir->rc->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
-	ir->rc->rx_resolution = SUNXI_IR_SAMPLE;
+	/* Frequency after IR internal divider with sample period in ns */
+	ir->rc->rx_resolution = (1000000000ul / (b_clk_freq / 64));
  	ir->rc->timeout = MS_TO_NS(SUNXI_IR_TIMEOUT);
  	ir->rc->driver_name = SUNXI_IR_DEV;

Thanks,
Mauro




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