Re: [PATCH v1 1/1] i2c: designware: Fix hold and setup time issue

[sathyanarayanan kuppuswamy]

On 06/02/2015 10:46 AM, Wolfram Sang wrote:

On Mon, Apr 06, 2015 at 07:40:28PM -0700, Kuppuswamy Sathyanarayanan wrote:

If the device configuration is updated by firmware and
the information is not passed to driver via firmware
interfaces like ACPI or DT parameters, then that information
will be lost once the device either resets or suspends. This
patch checks the boot value of hold and setup time during
device probe and updates the driver hold and setup time params.
This fix will ensure that the updates to hold and setup time
values are not lost after device suspend or resets.

Signed-off-by: Kuppuswamy Sathyanarayanan 
<sathyanarayanan.kuppusw...@linux.intel.com>

Adding Mika to CC.

---
  drivers/i2c/busses/i2c-designware-core.c    | 37 +++++++++++++++++++++++++++++
  drivers/i2c/busses/i2c-designware-core.h    |  2 ++
  drivers/i2c/busses/i2c-designware-platdrv.c |  4 ++++
  3 files changed, 43 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-core.c 
b/drivers/i2c/busses/i2c-designware-core.c
index 6e25c01..2598207 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -64,6 +64,7 @@
  #define DW_IC_RXFLR           0x78
  #define DW_IC_SDA_HOLD                0x7c
  #define DW_IC_TX_ABRT_SOURCE  0x80
+#define DW_IC_SDA_SETUP                0x94
  #define DW_IC_ENABLE_STATUS   0x9c
  #define DW_IC_COMP_PARAM_1    0xf4
  #define DW_IC_COMP_VERSION    0xf8
@@ -89,6 +90,9 @@
                                         DW_IC_INTR_TX_ABRT | \
                                         DW_IC_INTR_STOP_DET)

+#define DW_IC_DEFAULT_SDA_SETUP 0x64

+#define DW_IC_DEFAULT_SDA_HOLD 0x1
+
  #define DW_IC_STATUS_ACTIVITY 0x1

#define DW_IC_ERR_TX_ABRT 0x1

@@ -271,6 +275,35 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool 
enable)
                 enable ? "en" : "dis");
  }

+/*

+ * Update device default param values if its changed by
+ * firmware
+ */
+void dw_i2c_update_defaults(struct dw_i2c_dev *dev)
+{
+       int ret;
+
+       /*
+        * make sure default is not updated by firmware
+        * interfaces like OF or ACPI
+        */
+
+       /* SDA hold time update */
+       if (!dev->sda_hold_time) {
+               ret = dw_readl(dev, DW_IC_SDA_HOLD);
+               if ((ret > 0) && (ret != DW_IC_DEFAULT_SDA_HOLD))
+                       dev->sda_hold_time = ret;
+       }
+
+       /* SDA setup time update */
+       if (!dev->sda_setup_time) {
+               ret = dw_readl(dev, DW_IC_SDA_SETUP);
+               if ((ret > 0) && (ret != DW_IC_DEFAULT_SDA_SETUP))
+                       dev->sda_setup_time = ret;
+       }
+}
+EXPORT_SYMBOL_GPL(dw_i2c_update_defaults);
+
  /**
   * i2c_dw_init() - initialize the designware i2c master hardware
   * @dev: device private data
@@ -368,6 +401,10 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
                                "Hardware too old to adjust SDA hold time.");
        }

+ /* Configure SDA setup time if required */

+       if (dev->sda_setup_time)
+               dw_writel(dev, dev->sda_setup_time, DW_IC_SDA_SETUP);
+
        /* Configure Tx/Rx FIFO threshold levels */
        dw_writel(dev, dev->tx_fifo_depth / 2, DW_IC_TX_TL);
        dw_writel(dev, 0, DW_IC_RX_TL);
diff --git a/drivers/i2c/busses/i2c-designware-core.h 
b/drivers/i2c/busses/i2c-designware-core.h
index 9630222..23ae2e8 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -98,6 +98,7 @@ struct dw_i2c_dev {
        unsigned int            rx_fifo_depth;
        int                     rx_outstanding;
        u32                     sda_hold_time;
+       u32                     sda_setup_time;
        u32                     sda_falling_time;
        u32                     scl_falling_time;
        u16                     ss_hcnt;
@@ -131,3 +132,4 @@ extern int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev);
  #else
  static inline int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev) { return 
0; }
  #endif
+extern void dw_i2c_update_defaults(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c 
b/drivers/i2c/busses/i2c-designware-platdrv.c
index c270f5f..d8995d8 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -233,6 +233,10 @@ static int dw_i2c_probe(struct platform_device *pdev)
                dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
                dev->adapter.nr = pdev->id;
        }
+
+       /* call after firmware param update */
+       dw_i2c_update_defaults(dev);

What about calling this from the pci driver?

Agreed. I will fix it in next version.

--
Sathyanarayanan Kuppuswamy
Android kernel developer

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