[PATCH 03/14] coresight: tmc: re-implementing tmc_read_prepare/unprepare() functions

On 23 March 2016 at 04:37, Suzuki K. Poulose [off-list ref] wrote:

On 22/03/16 20:23, Mathieu Poirier wrote:

quoted

In their current implementation the tmc_read_prepare/unprepare()
are a lump of if/else that is difficult to read.  This patch is
alleviating that by using a switch statement.  The latter also
allows for a better control on the error path.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
  drivers/hwtracing/coresight/coresight-tmc.c | 56
++++++++++++++++++-----------
  1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc.c

b/drivers/hwtracing/coresight/coresight-tmc.c
index f4ba837a0810..208d47dd3083 100644

--- a/drivers/hwtracing/coresight/coresight-tmc.c
+++ b/drivers/hwtracing/coresight/coresight-tmc.c

@@ -430,7 +430,7 @@ static const struct coresight_ops tmc_etf_cs_ops = {

quoted

-       if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
+       switch (drvdata->config_type) {
+       case TMC_CONFIG_TYPE_ETB:
                tmc_etb_disable_hw(drvdata);
-       } else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
-               tmc_etr_disable_hw(drvdata);
-       } else {
+               break;
+       case TMC_CONFIG_TYPE_ETF:
+               /* There is no point in reading a TMC in HW FIFO mode */
                mode = readl_relaxed(drvdata->base + TMC_MODE);
-               if (mode == TMC_MODE_CIRCULAR_BUFFER) {
-                       tmc_etb_disable_hw(drvdata);
-               } else {
-                       ret = -ENODEV;
+               if (mode != TMC_MODE_CIRCULAR_BUFFER) {
+                       ret = -EINVAL;
                        goto err;
                }
+
+               tmc_etb_disable_hw(drvdata);
+               break;
+       case TMC_CONFIG_TYPE_ETR:
+               tmc_etr_disable_hw(drvdata);
+               break;
+       default:
+               ret = -EINVAL;
+               goto err;
        }

We seem to be doing this switch at different places in the code just for
enable_hw/disable_hw.
e.g, tmc_enable, tmc_disable

Could we make this a bit more cleaner by introducing something like this ?

struct tmc_hw_ops {
        int (*enable_hw)(struct tmc_drvdata *drvdata, enum tmc_mode mode);
        int (*disable_hw)(struct tmc_drvdata *drvdata, enum tmc_mode mode);
};

struct tmc_hw_ops tmc_etf_ops = {
        tmc_etf_enable_hw,
        tmc_etf_disable_hw,
};

similiarly for etb and etr and then add struct tmc_hw_ops *hw_ops to
tmc_drvdata, initialised
at probe time (while reading the config_type).

That is a good idea - let me experiment with it a little...

Suzuki