2016-12-06 07:58:45

by Tin Huynh

Subject: [PATCH V2] i2c: designware: fix wrong tx/rx fifo for ACPI

ACPI always sets txfifo and rxfifo to 32. This configuration will
cause problem if the IP core supports a fifo size of less than 32.
The driver should read the fifo size from the IP and select the
smaller one of the two.

Signed-off-by: Tin Huynh <[email protected]>

---
drivers/i2c/busses/i2c-designware-platdrv.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)

Change from V1:
-Revert the default 32 for fifo, read parameter from IP core
and pick the smaller one of the two.
-Correct the title to describe new approach.

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 0b42a12..76b061f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -153,6 +153,7 @@ static int i2c_dw_plat_prepare_clk(struct dw_i2c_dev *i_dev, bool prepare)
static int dw_i2c_plat_probe(struct platform_device *pdev)
{
struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
+ u32 param1, tx_fifo_depth, rx_fifo_depth;
struct dw_i2c_dev *dev;
struct i2c_adapter *adap;
struct resource *mem;
@@ -246,12 +247,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
1000000);
}

+ param1 = i2c_dw_read_comp_param(dev);
+ tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
+ rx_fifo_depth = ((param1 >> 8) & 0xff) + 1;
if (!dev->tx_fifo_depth) {
- u32 param1 = i2c_dw_read_comp_param(dev);
-
- dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
- dev->rx_fifo_depth = ((param1 >> 8) & 0xff) + 1;
+ dev->tx_fifo_depth = tx_fifo_depth;
+ dev->rx_fifo_depth = rx_fifo_depth;
dev->adapter.nr = pdev->id;
+ } else if (tx_fifo_depth) {
+ dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
+ tx_fifo_depth);
+ dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
+ rx_fifo_depth);
}

adap = &dev->adapter;
--
1.7.1

2016-12-07 10:15:17

by Andy Shevchenko

Subject: Re: [PATCH V2] i2c: designware: fix wrong tx/rx fifo for ACPI

On Tue, 2016-12-06 at 14:57 +0700, Tin Huynh wrote:
> ACPI always sets txfifo and rxfifo to 32. This configuration will
> cause problem if the IP core supports a fifo size of less than 32.
> The driver should read the fifo size from the IP and select the 
> smaller one of the two.
>
> Signed-off-by: Tin Huynh <[email protected]>
>

The idea looks good, but see my comment below.

> >dev);
> + u32 param1, tx_fifo_depth, rx_fifo_depth;
>   struct dw_i2c_dev *dev;
>   struct i2c_adapter *adap;
>   struct resource *mem;
> @@ -246,12 +247,18 @@ static int dw_i2c_plat_probe(struct
> platform_device *pdev)
>   1000000);
>   }
>  
> + param1 = i2c_dw_read_comp_param(dev);
> + tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> + rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
>   if (!dev->tx_fifo_depth) {
> - u32 param1 = i2c_dw_read_comp_param(dev);
> -
> - dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> - dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> + dev->tx_fifo_depth = tx_fifo_depth;
> + dev->rx_fifo_depth = rx_fifo_depth;
>   dev->adapter.nr = pdev->id;
> + } else if (tx_fifo_depth) {
> + dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
> + tx_fifo_depth
> );
> + dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
> + rx_fifo_dept

Can we move this to a separate function like

static void dw_i2c_set_fifo_size(... *dev, ... id)
{
u32 param, tx_fifo_depth, rx_fifo_depth;

param = i2c_dw_read_comp_param(dev);
tx_fifo_depth = ((param >> 16) & 0xff) + 1;
rx_fifo_depth = ((param >> 8)  & 0xff) + 1;

  if (!dev->tx_fifo_depth) {
dev->tx_fifo_depth = tx_fifo_depth;
dev->rx_fifo_depth = rx_fifo_depth;
  dev->adapter.nr = id;
}

dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
tx_fifo_depth);
dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
rx_fifo_depth);
}

?

--
Andy Shevchenko <[email protected]>
Intel Finland Oy