Vishwanath Sripathy <vishwanath.bs@xxxxxx> writes: >> -----Original Message----- >> From: Kevin Hilman [mailto:khilman@xxxxxx] >> Sent: Friday, February 04, 2011 9:35 PM >> To: Vishwanath BS >> Cc: linux-omap@xxxxxxxxxxxxxxx; patches@xxxxxxxxxx; Thara Gopinath >> Subject: Re: [PATCH 05/13] OMAP: Introduce device scale >> implementation >> >> Vishwanath BS <vishwanath.bs@xxxxxx> writes: >> >> > This patch adds omap_device_scale API which can be used to generic >> > device rate scaling. >> >> I would've expected a new omap_device_* API to be part of the >> omap_device layer, not added here. > Given that this API does not deal with any of the omap_device layer > functions or data structures, I am not sure if it logically belongs to > omap device layer. If you think it should belong to omap_device layer just > because the name starts with omap_device, I would rather rename this API. That's up to you. But if it's not an omap_device API, then it shouldn't be named omap_device_* Kevin >> >> > Based on original patch from Thara. >> > >> > Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx> >> > Cc: Thara Gopinath <thara@xxxxxx> >> > --- >> > arch/arm/mach-omap2/dvfs.c | 116 >> ++++++++++++++++++++++++++++++++ >> > arch/arm/plat-omap/include/plat/dvfs.h | 7 ++ >> > 2 files changed, 123 insertions(+), 0 deletions(-) >> > >> > diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach- >> omap2/dvfs.c >> > index c9d3894..05a9ce3 100755 >> > --- a/arch/arm/mach-omap2/dvfs.c >> > +++ b/arch/arm/mach-omap2/dvfs.c >> > @@ -19,6 +19,7 @@ >> > #include <plat/common.h> >> > #include <plat/voltage.h> >> > #include <plat/omap_device.h> >> > +#include <plat/smartreflex.h> >> > >> > /** >> > * struct omap_dev_user_list - Structure maitain userlist per device >> > @@ -585,6 +586,121 @@ static int omap_dvfs_voltage_scale(struct >> omap_vdd_dvfs_info *dvfs_info) >> > } >> > >> > /** >> > + * omap_device_scale() - Set a new rate at which the device is to >> operate >> > + * @req_dev: pointer to the device requesting the scaling. >> > + * @target_dev: pointer to the device that is to be scaled >> > + * @rate: the rnew rate for the device. >> > + * >> > + * This API gets the device opp table associated with this device and >> > + * tries putting the device to the requested rate and the voltage >> domain >> > + * associated with the device to the voltage corresponding to the >> > + * requested rate. Since multiple devices can be assocciated with a >> > + * voltage domain this API finds out the possible voltage the >> > + * voltage domain can enter and then decides on the final device >> > + * rate. Return 0 on success else the error value >> > + */ >> >> Here would be a good place to describe why both the requesting device >> and the target device need to be tracked. > OK > >> >> > +int omap_device_scale(struct device *req_dev, struct device >> *target_dev, >> > + unsigned long rate) >> > +{ >> > + struct opp *opp; >> > + unsigned long volt, freq, min_freq, max_freq; >> > + struct omap_vdd_dvfs_info *dvfs_info; >> > + struct platform_device *pdev; >> > + struct omap_device *od; >> > + int ret = 0; >> > + >> > + pdev = container_of(target_dev, struct platform_device, dev); >> > + od = container_of(pdev, struct omap_device, pdev); >> > + >> > + /* >> > + * Figure out if the desired frquency lies between the >> > + * maximum and minimum possible for the particular device >> > + */ >> > + min_freq = 0; >> > + if (IS_ERR(opp_find_freq_ceil(target_dev, &min_freq))) { >> > + dev_err(target_dev, "%s: Unable to find lowest opp\n", >> > + __func__); >> > + return -ENODEV; >> > + } >> > + >> > + max_freq = ULONG_MAX; >> > + if (IS_ERR(opp_find_freq_floor(target_dev, &max_freq))) { >> > + dev_err(target_dev, "%s: Unable to find highest opp\n", >> > + __func__); >> > + return -ENODEV; >> > + } >> > + >> > + if (rate < min_freq) >> > + freq = min_freq; >> > + else if (rate > max_freq) >> > + freq = max_freq; >> > + else >> > + freq = rate; >> > + >> >> OK, frome here on, I would expect the adjusted value 'freq' to be used >> instead of 'rate', but that is not the case below. >> >> > + opp = opp_find_freq_ceil(target_dev, &freq); >> > + if (IS_ERR(opp)) { >> > + dev_err(target_dev, "%s: Unable to find OPP for >> freq%ld\n", >> > + __func__, rate); >> > + return -ENODEV; >> > + } > Freq is appropriate than rate here. Will fix it. >> > + >> > + /* Get the voltage corresponding to the requested frequency */ >> > + volt = opp_get_voltage(opp); >> > + >> > + /* >> > + * Call into the voltage layer to get the final voltage possible >> > + * for the voltage domain associated with the device. >> > + */ >> >> This comment doesn't match the following code. > OK. Will fix it. Copy paste error. >> >> > + if (rate) { >> >> Why is rate used here, and not freq? > Freq can never be 0. If somebody wants to remove his DVFS request (he does > not really care about the device frequency), then he can pass rate as 0. > Hence rate is used. >> >> > + dvfs_info = get_dvfs_info(od->hwmods[0]->voltdm); >> > + >> > + ret = omap_dvfs_add_freq_request(dvfs_info, req_dev, >> > + target_dev, freq); >> > + if (ret) { >> > + dev_err(target_dev, "%s: Unable to add frequency >> request\n", >> > + __func__); >> > + return ret; >> > + } >> > + >> > + ret = omap_dvfs_add_vdd_user(dvfs_info, req_dev, volt); >> > + if (ret) { >> > + dev_err(target_dev, "%s: Unable to add voltage >> request\n", >> > + __func__); >> > + omap_dvfs_remove_freq_request(dvfs_info, >> req_dev, >> > + target_dev); >> > + return ret; >> > + } >> > + } else { >> >> The function comments don't describe this case. Namely, that if you >> pass in rate = 0, it removes any previous requests for the requesting >> device. > OK. Will add that in function comments. >> >> > + dvfs_info = get_dvfs_info(od->hwmods[0]->voltdm); >> > + >> > + ret = omap_dvfs_remove_freq_request(dvfs_info, >> req_dev, >> > + target_dev); >> > + if (ret) { >> > + dev_err(target_dev, "%s: Unable to remove >> frequency request\n", >> > + __func__); >> > + return ret; >> > + } >> > + >> > + ret = omap_dvfs_remove_vdd_user(dvfs_info, req_dev); >> > + if (ret) { >> > + dev_err(target_dev, "%s: Unable to remove voltage >> request\n", >> > + __func__); >> > + return ret; >> > + } >> > + } >> > + >> > + /* Do the actual scaling */ >> > + ret = omap_dvfs_voltage_scale(dvfs_info); >> >> ok >> >> > + if (!ret) >> > + if (omap_device_get_rate(target_dev) >= rate) >> > + return 0; >> > + >> >> but this bit needs some explanation. IIUC: if the _voltage_scale() >> fails (which also scales the frequency) but the frequency was >> sucessfully changed, then return success. > Yes, this is basically to cater for situations where some of the devices > in the associated vdd have locked their frequencies. In that case, voltage > scaling would not have happened where as frequency for the requested > device has been set successfully. In that case return success. Will add > these in function comments. >> >> Also 'rate' is used here where 'freq' would be expected. > OK. Will fix it. > > Vishwa >> >> > + return ret; >> > +} >> > +EXPORT_SYMBOL(omap_device_scale); >> > + >> > +/** >> > * omap_dvfs_init() - Initialize omap dvfs layer >> > * >> > * Initalizes omap dvfs layer. It basically allocates memory for >> > diff --git a/arch/arm/plat-omap/include/plat/dvfs.h b/arch/arm/plat- >> omap/include/plat/dvfs.h >> > index 1302990..1be2b9d 100644 >> > --- a/arch/arm/plat-omap/include/plat/dvfs.h >> > +++ b/arch/arm/plat-omap/include/plat/dvfs.h >> > @@ -17,11 +17,18 @@ >> > >> > #ifdef CONFIG_PM >> > int omap_dvfs_register_device(struct voltagedomain *voltdm, struct >> device *dev); >> > +int omap_device_scale(struct device *req_dev, struct device *dev, >> > + unsigned long rate); >> > #else >> > static inline int omap_dvfs_register_device(struct voltagedomain >> *voltdm, >> > struct device *dev) >> > { >> > return -EINVAL; >> > } >> > +static inline int omap_device_scale(struct device *req_dev, struct >> devices >> > + *target_dev, unsigned long rate); >> > +{ >> > + return -EINVAL; >> > +} >> > #endif >> > #endif >> >> Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
