Hi Mika,

On 12/18/2015 4:13 AM, Mika Westerberg wrote:
[....]
So instead of this, what if we do not assign dev->get_clk_rate_khz at
all and then do something like below in the core driver?

I like the changes below since it is clear to see within the core file how things are handled when get_clk_rate_khz is not assigned (i.e. input_clock_hz = 0), and not necessary relying on the platform driver to return 0 in this case.

So, at this point, I can re-submit the V3 and combine these changes, and we both can sign-off. How does that sound?

Thanks,
Suravee

Of course we still need the other changes you did in this patch to cope
with the missing clock.

diff --git a/drivers/i2c/busses/i2c-designware-core.c 
b/drivers/i2c/busses/i2c-designware-core.c
index 8c48b27ba059..25dccd8df772 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -271,6 +271,17 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool 
enable)
                 enable ? "en" : "dis");
  }

+static unsigned long i2c_dw_clk_rate(struct dw_i2c_dev *dev)
+{
+       /*
+        * Clock is not necessary if we got LCNT/HCNT values directly from
+        * the platform code.
+        */
+       if (WARN_ON_ONCE(!dev->get_clk_rate_khz))
+               return 0;
+       return dev->get_clk_rate_khz(dev);
+}
+
  /**
   * i2c_dw_init() - initialize the designware i2c master hardware
   * @dev: device private data
@@ -281,7 +292,6 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool 
enable)
   */
  int i2c_dw_init(struct dw_i2c_dev *dev)
  {
-       u32 input_clock_khz;
        u32 hcnt, lcnt;
        u32 reg;
        u32 sda_falling_time, scl_falling_time;
@@ -295,8 +305,6 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
                }
        }

-       input_clock_khz = dev->get_clk_rate_khz(dev);
-
        reg = dw_readl(dev, DW_IC_COMP_TYPE);
        if (reg == ___constant_swab32(DW_IC_COMP_TYPE_VALUE)) {
                /* Configure register endianess access */
@@ -325,12 +333,12 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
                hcnt = dev->ss_hcnt;
                lcnt = dev->ss_lcnt;
        } else {
-               hcnt = i2c_dw_scl_hcnt(input_clock_khz,
+               hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
                                        4000,   /* tHD;STA = tHIGH = 4.0 us */
                                        sda_falling_time,
                                        0,      /* 0: DW default, 1: Ideal */
                                        0);     /* No offset */
-               lcnt = i2c_dw_scl_lcnt(input_clock_khz,
+               lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
                                        4700,   /* tLOW = 4.7 us */
                                        scl_falling_time,
                                        0);     /* No offset */
@@ -344,12 +352,12 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
                hcnt = dev->fs_hcnt;
                lcnt = dev->fs_lcnt;
        } else {
-               hcnt = i2c_dw_scl_hcnt(input_clock_khz,
+               hcnt = i2c_dw_scl_hcnt(i2c_dw_clk_rate(dev),
                                        600,    /* tHD;STA = tHIGH = 0.6 us */
                                        sda_falling_time,
                                        0,      /* 0: DW default, 1: Ideal */
                                        0);     /* No offset */
-               lcnt = i2c_dw_scl_lcnt(input_clock_khz,
+               lcnt = i2c_dw_scl_lcnt(i2c_dw_clk_rate(dev),
                                        1300,   /* tLOW = 1.3 us */
                                        scl_falling_time,
                                        0);     /* No offset */


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