Re: [PATCH V2 12/15] coresight: tmc: keep track of memory width

[Suzuki K Poulose]

On 12/04/16 18:54, Mathieu Poirier wrote:

Accessing the HW configuration register each time the memory
width is needed simply doesn't make sense.  It is much more
efficient to read the value once and keep a reference for
later use.

Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
  drivers/hwtracing/coresight/coresight-tmc-etf.c | 8 +++-----
  drivers/hwtracing/coresight/coresight-tmc.c     | 1 +
  drivers/hwtracing/coresight/coresight-tmc.h     | 2 ++
  3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c 
b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 50d32e8ef4ea..a440784e3b27 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -41,18 +41,16 @@ void tmc_etb_enable_hw(struct tmc_drvdata *drvdata)

  static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
  {
-       enum tmc_mem_intf_width memwidth;
        u8 memwords;
        char *bufp;
        u32 read_data;
        int i;

-       memwidth = BMVAL(readl_relaxed(drvdata->base + CORESIGHT_DEVID), 8, 10);
-       if (memwidth == TMC_MEM_INTF_WIDTH_32BITS)
+       if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_32BITS)
                memwords = 1;
-       else if (memwidth == TMC_MEM_INTF_WIDTH_64BITS)
+       else if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_64BITS)
                memwords = 2;
-       else if (memwidth == TMC_MEM_INTF_WIDTH_128BITS)
+       else if (drvdata->memwidth == TMC_MEM_INTF_WIDTH_128BITS)
                memwords = 4;

  struct tmc_drvdata {
@@ -118,6 +119,7 @@ struct tmc_drvdata {
        u32                     size;
        local_t                 mode;
        enum tmc_config_type    config_type;
+       enum tmc_mem_intf_width memwidth;

Could we not store the converted memwords here, instead of the enum value here
and convert it every time we access it ?

Cheers
Suzuki