| Message ID | 1458678202-3447-4-git-send-email-mathieu.poirier@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 23 March 2016 at 04:37, Suzuki K. Poulose <Suzuki.Poulose@arm.com> wrote: > On 22/03/16 20:23, Mathieu Poirier wrote: >> >> 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 = { >> > >> - 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 >
On 23 March 2016 at 04:37, Suzuki K. Poulose <Suzuki.Poulose@arm.com> wrote: > On 22/03/16 20:23, Mathieu Poirier wrote: >> >> 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 = { >> > >> - 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). So I started to look into implementing your proposition. In this patch adding a new hw_ops does make sense but the next few patches keep cleaning up the code even further, with a very clean and neat end result [1]. We could still optimise things further but not by a lot. In the end would will likely end up with the same amount of code (maybe a little more) without much gain. Performance wise the hit taken by the case statement is negligible, even more so since the code is only driven by user space. As such I don't think there is much to gain by moving ahead with this - get back to me if you feel otherwise. Thanks for the review, Mathieu [1]. https://git.linaro.org/people/mathieu.poirier/coresight.git/blob/refs/heads/perf-opencsd-4.5:/drivers/hwtracing/coresight/coresight-tmc.c#l75 > > > Suzuki >
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 = { static int tmc_read_prepare(struct tmc_drvdata *drvdata) { - int ret; + int ret = 0; unsigned long flags; enum tmc_mode mode; @@ -438,25 +438,31 @@ static int tmc_read_prepare(struct tmc_drvdata *drvdata) if (!drvdata->enable) goto out; - 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; } + out: drvdata->reading = true; - spin_unlock_irqrestore(&drvdata->spinlock, flags); - dev_info(drvdata->dev, "TMC read start\n"); - return 0; err: spin_unlock_irqrestore(&drvdata->spinlock, flags); return ret; @@ -471,20 +477,30 @@ static void tmc_read_unprepare(struct tmc_drvdata *drvdata) if (!drvdata->enable) goto out; - if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) { + switch (drvdata->config_type) { + case TMC_CONFIG_TYPE_ETB: tmc_etb_enable_hw(drvdata); - } else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) { - tmc_etr_enable_hw(drvdata); - } else { + break; + case TMC_CONFIG_TYPE_ETF: + /* Make sure we don't re-enable a TMC in HW FIFO mode */ mode = readl_relaxed(drvdata->base + TMC_MODE); - if (mode == TMC_MODE_CIRCULAR_BUFFER) - tmc_etb_enable_hw(drvdata); + if (mode != TMC_MODE_CIRCULAR_BUFFER) + goto err; + + tmc_etb_enable_hw(drvdata); + break; + case TMC_CONFIG_TYPE_ETR: + tmc_etr_disable_hw(drvdata); + break; + default: + goto err; } + out: drvdata->reading = false; - spin_unlock_irqrestore(&drvdata->spinlock, flags); - dev_info(drvdata->dev, "TMC read end\n"); +err: + spin_unlock_irqrestore(&drvdata->spinlock, flags); } static int tmc_open(struct inode *inode, struct file *file)
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(-)