On 17/07/15 11:25, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Mon, Jul 13, 2015 at 01:39:46PM +0100, Jon Hunter wrote:
>> The following clean-ups have been made to the PMC code:
>>
>> 1. Add a macro for determining the state of a PMC powergate
>> 2. Use the readx_poll_timeout() function instead of implementing a local
>> polling loop with a timeout.
>> 3. Use a case-statement in the function that removes the powergate clamp
>> instead of multiple if-statements to improve readability.
>>
>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
>> ---
>> drivers/soc/tegra/pmc.c | 72 ++++++++++++++++++++++++-------------------------
>> 1 file changed, 35 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>> index c0635bdd4ee3..180d434deec5 100644
>> --- a/drivers/soc/tegra/pmc.c
>> +++ b/drivers/soc/tegra/pmc.c
>> @@ -28,6 +28,7 @@
>> #include <linux/export.h>
>> #include <linux/init.h>
>> #include <linux/io.h>
>> +#include <linux/iopoll.h>
>> #include <linux/of.h>
>> #include <linux/of_address.h>
>> #include <linux/platform_device.h>
>> @@ -56,6 +57,8 @@
>> #define PWRGATE_TOGGLE_START (1 << 8)
>>
>> #define REMOVE_CLAMPING 0x34
>> +#define REMOVE_CLAMPING_VDEC (1 << 3)
>> +#define REMOVE_CLAMPING_PCIE (1 << 4)
>>
>> #define PWRGATE_STATUS 0x38
>>
>> @@ -101,6 +104,8 @@
>>
>> #define GPU_RG_CNTRL 0x2d4
>>
>> +#define PMC_PWRGATE_STATE(val, id) (!!(val & BIT(id)))
>
> I find double-negations very difficult to read. ((value & BIT(id)) != 0)
> is clearer in my opinion. Also I'd suggest status or value as the first
> parameter name, for consistency with other parts of the driver.
>
>> +
>> struct tegra_pmc_soc {
>> unsigned int num_powergates;
>> const char *const *powergates;
>> @@ -177,15 +182,14 @@ static void tegra_pmc_writel(u32 value, unsigned long offset)
>> */
>> static int tegra_powergate_set(int id, bool new_state, bool wait)
>> {
>> - unsigned long timeout;
>> - bool status;
>> int ret = 0;
>> + u32 val;
>>
>> mutex_lock(&pmc->powergates_lock);
>>
>> - status = tegra_pmc_readl(PWRGATE_STATUS) & (1 << id);
>> + val = tegra_pmc_readl(PWRGATE_STATUS);
>>
>> - if (status == new_state) {
>> + if (PMC_PWRGATE_STATE(val, id) == new_state) {
>> mutex_unlock(&pmc->powergates_lock);
>> return 0;
>> }
>> @@ -193,17 +197,9 @@ static int tegra_powergate_set(int id, bool new_state, bool wait)
>> tegra_pmc_writel(PWRGATE_TOGGLE_START | id, PWRGATE_TOGGLE);
>>
>> if (wait) {
>> - timeout = jiffies + msecs_to_jiffies(100);
>> - ret = -ETIMEDOUT;
>> -
>> - while (time_before(jiffies, timeout)) {
>> - status = !!(tegra_pmc_readl(PWRGATE_STATUS) & BIT(id));
>> - if (status == new_state) {
>> - ret = 0;
>> - break;
>> - }
>> - udelay(10);
>> - }
>> + ret = readx_poll_timeout(tegra_pmc_readl, PWRGATE_STATUS,
>> + val, PMC_PWRGATE_STATE(val, id) == new_state,
>> + 10, 100000);
>> }
>>
>> mutex_unlock(&pmc->powergates_lock);
>> @@ -242,13 +238,10 @@ EXPORT_SYMBOL(tegra_powergate_power_off);
>> */
>> int tegra_powergate_is_powered(int id)
>> {
>> - u32 status;
>> -
>> if (!pmc->soc || id < 0 || id >= pmc->soc->num_powergates)
>> return -EINVAL;
>>
>> - status = tegra_pmc_readl(PWRGATE_STATUS) & (1 << id);
>> - return !!status;
>> + return PMC_PWRGATE_STATE(tegra_pmc_readl(PWRGATE_STATUS), id);
>
> I'd prefer to keep the two steps here. As a general rule I try never to
> mix reading or writing a register with other code on the same line.
>
>> }
>>
>> /**
>> @@ -257,34 +250,39 @@ int tegra_powergate_is_powered(int id)
>> */
>> int tegra_powergate_remove_clamping(int id)
>> {
>> - u32 mask;
>> + u32 val, reg;
>
> Side note: Please use value instead of val since that's the form used
> elsewhere in the driver. Also reg would be more appropriately called
> offset or similar because that's what it really is. It would also be
> more naturally an unsized type, such as unsigned int. But...
>
>>
>> if (!pmc->soc || id < 0 || id >= pmc->soc->num_powergates)
>> return -EINVAL;
>>
>> /*
>> - * On Tegra124 and later, the clamps for the GPU are controlled by a
>> - * separate register (with different semantics).
>> + * In most cases the bit for removing the IO clamping is the same as
>> + * the powergate partition ID, however, this is not always the case.
>> + * Furthermore, on Tegra124 and later, the clamps for the GPU are
>> + * controlled by a separate register (with different semantics). The
>> + * following case-statement handles these exceptions.
>> */
>> - if (id == TEGRA_POWERGATE_3D) {
>> + val = 1 << id;
>> + reg = REMOVE_CLAMPING;
>> +
>> + switch (id) {
>> + case TEGRA_POWERGATE_3D:
>> if (pmc->soc->has_gpu_clamps) {
>> - tegra_pmc_writel(0, GPU_RG_CNTRL);
>> - return 0;
>> + val = 0;
>> + reg = GPU_RG_CNTRL;
>> }
>> + break;
>> + case TEGRA_POWERGATE_VDEC:
>> + val = REMOVE_CLAMPING_VDEC;
>> + break;
>> + case TEGRA_POWERGATE_PCIE:
>> + val = REMOVE_CLAMPING_PCIE;
>> + break;
>> + default:
>> + break;
>> }
>>
>> - /*
>> - * Tegra 2 has a bug where PCIE and VDE clamping masks are
>> - * swapped relatively to the partition ids
>> - */
>> - if (id == TEGRA_POWERGATE_VDEC)
>> - mask = (1 << TEGRA_POWERGATE_PCIE);
>> - else if (id == TEGRA_POWERGATE_PCIE)
>> - mask = (1 << TEGRA_POWERGATE_VDEC);
>> - else
>> - mask = (1 << id);
>> -
>> - tegra_pmc_writel(mask, REMOVE_CLAMPING);
>> + tegra_pmc_writel(val, reg);
>
> ... to be honest, I think the previous code was more straightforward, so
> I'd prefer if you dropped this particular hunk.
Ok, I will drop that part. Jon
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