Hello Nishanth and Kevin, On Thu, Nov 26, 2009 at 01:22:49AM +0100, ext Nishanth Menon wrote: > Kevin Hilman had written, on 11/25/2009 05:46 PM, the following: > [...] > >>> something like this instead: > >>> > >>> /** > >>> * opp_find_freq() > >>> * @oppl: OPP list > >>> * @freq: Frequency to look for in OPP table > >>> * > >>> * Look for an enabled OPP with a frequency value matching @freq. > >>> * > >>> * Returns pointer to OPP entry if match is found, or NULL if no match > >>> * found. > >>> */ > >>> struct omap_opp *opp_find_freq(const struct omap_opp *oppl, u32 freq); > >> I did think about it(single function doing multiple things), the > >> intention is as follows in reality: > >> opp_is_valid : Search only for enabled frequencies > >> opp_has_freq : Searches for enabled/disabled frequencies > >> > >> This is useful for some logic which wants to enable a frequency which > >> may have been disabled in the table. now, to retain that > >> functionality, > >> A) > >> /** > >> * opp_find_freq() - Find a opp corresponding to frequency > >> * @oppl: opp list to search > >> * @freq: frequency to loopup in OPP table > >> * @enabled: search only enabled frequencies > >> * > >> * return opp handle corresponding to the frequency found, else > >> * return NULL. Search for enabled frequencies if enabled flag > >> * is true, else search for disabled frequencies also > >> */ > >> struct omap_opp *opp_find_freq(const struct omap_opp *oppl, > >> unsigned long freq, bool enabled); > >> > >> This will handle the functionalities that are supported in rev 3. > >> > >> B) I rename existing functions: > >> opp_has_freq ==> opp_is_disabled() > >> opp_is_valid ==> opp_is_enabled() > >> > >> I would still prefer to go with explicit function search APIs.. > > > > I like (A) here. > Ack. I can see it useful if we go to a list iterator at a later point of time. > [...] > > >>> /** > >>> * opp_find_freq_rounded() > >>> * @oppl: OPP list > >>> * @freq: Frequency to look for in OPP table > >>> * @rounding: Rounding option: NONE, UP, DOWN > >>> * > >>> * Look for an OPP with a frequency value matching @freq. If > >>> * @rounding != ROUND_NONE, find closest match using rounding. > >>> * > >>> * Can be used to find exact OPP, or match using given rounding: > >>> > >>> * @rounding == UP: find next highest frequency > >>> * @rounding == DOWN: find next lowest frequency > >>> * @rounding == CLOSEST: find closest frequency > >>> * > >>> * Returns pointer to OPP entry if match is found, or NULL if no match > >>> * found (only possible when no rounding is used) > >>> */ > >>> struct omap_opp *opp_find_freq_rounded(struct omap_opp *oppl, u32 freq, u32 rounding); > >>> > >>> Looking at the users of the 'higher' and 'lower' OPPs in the current > >>> code, I see that SRF tries to use all three one after the other. > >>> First it checks for exact match, then for higher, then for lower. > >>> This could be replaced simply by doing a 'closest' match. > >> hmmm.. I think we are going a full circle here. > >> > >> /* Search exact frequency */ > >> #define OPP_ROUND_NONE (0 << 0) > >> /* Search approx frequency */ > >> #define OPP_ROUND_CLOSEST (1 << 0) > >> /* Search up */ > >> #define OPP_ROUND_HIGH (0 << 1) > >> /* Search down */ > >> #define OPP_ROUND_LOW (1 << 1) > >> > >> struct omap_opp *opp_find_freq_rounded(struct omap_opp *oppl, > >> unsigned long freq, u8 rounding_flag); > >> > >> Note: the only difference b/w this and opp_find_freq is that > >> opp_find_freq will also search for enabled/disabled. > >> If I add that here, this is exactly the #1 implementation I did in > >> http://marc.info/?l=linux-omap&m=125800489123496&w=2 > >> ok, I used bool instead of a #define and added the complexity of using > >> enabled flag also: > >> > >> bool search_higher, bool search_enabled_only, bool exact_search > >> > >> what you are proposing is that I go back to my implementation #1 and > >> remove my bools instead by adding #defines: > >> /* Search up */ > >> #define OPP_ROUND_ENABLED (0 << 2) > >> /* Search down */ > >> #define OPP_ROUND_ANY (1 << 2) > >> > >> would even make the find_freq redundant.. > >> > >> Now, in your comment in > >> http://marc.info/?l=linux-omap&m=125816031406704&w=2 quote:"I think > >> all the options to this function make it not terribly > >> readable." > >> > >> Does it become any different now? > >> > > > > Yeah, I still think multiple bools to a function is a readability > > problem. Every time you look at a call, you have to look at the > > prototype to remember what all the options are. A single bool or flag > > is better IMHO. > > > >> without taking this in, exact searches can be done by specific > >> functions and approximate searches by another function.. we go > >> generic functions or we go specific functions.. generic comments I > >> have been getting is to go specific, hence the v2 and v3 series. > > > > OK, you're right. I am causing us to go around in circles now, but > > we're going around in increasingly smaller circles and hopefully > > converging on the target. ;) > Yep :) > > > > > So what I propose is having two functions. One for exact matches > > (your proposal A above) and one for approximate matches which is > > something like my find_freq_rounded(), but should maybe be renamed > > something like opp_find_freq_approx() or something. > > OK - Signed-Off. prototypes again :) > > Dead functions: opp_has_freq, opp_is_valid, opp_find_freq and other searches. > > Only two of them remain: (git diff follows) > opp_find_freq_approx > > opp_find_freq_exact > > > [..] > >> int __init opp_add(struct omap_opp **oppl, const struct omap_opp_def > >> *opp_defs); > > > > Mostly, but I was thinking of an API for adding a *single* OPP. The > > init code would iterate over its opp_def table adding OPPs one at a > > time resultingin multiple calls to opp_add(). > > > > OK, now I'm going around in circles again, but thinking more about his > > we probably need your original opp_init() which will create an empty > > master list, then repeated calls to opp_add() to add each OPP to the > > master list. > > Opp_init will be a subcase of opp_add. Giving opp_add capabiity to take > More than one def is useful for us in the long run: > a) You can add bunch of them without list iterator repeating in each and every adding code. > b) You can still add a single one if you choose to. > c) add to a NULL list == init the list. That does sound implicit to me, but if we want to create a singular function for it alone, then I recommend: > > lets just have opp_init, then see if we need to add opp_add -> none of the systems are mature enough for us to use it.. > > I am open either way. > > > > > Also does add need to be __init? Not sure why we would need to add > > OPPs after boot time if we have the ability to enable/disable them at > > runtime, but just a thought. > Removed.. if in case we would like to do an opp_add at some point. > > > > [...] > > > diff --git a/arch/arm/plat-omap/include/plat/opp.h b/arch/arm/plat-omap/include/plat/opp.h > new file mode 100644 > index 0000000..4a00685 > --- /dev/null > +++ b/arch/arm/plat-omap/include/plat/opp.h > @@ -0,0 +1,184 @@ > +/* > + * OMAP OPP Interface > + * > + * Copyright (C) 2009 Texas Instruments Incorporated. > + * Nishanth Menon > + * Copyright (C) 2009 Deep Root Systems, LLC. > + * Kevin Hilman > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > +#ifndef __ASM_ARM_OMAP_OPP_H > +#define __ASM_ARM_OMAP_OPP_H > + > +/** > + * struct omap_opp - OMAP OPP description structure > + * @enabled: true/false - marking this OPP as enabled/disabled > + * @rate: Frequency in hertz > + * @opp_id: (DEPRECATED) opp identifier > + * @vsel: Voltage in volt processor level(this usage is > + * DEPRECATED to use Voltage in microvolts in future) > + * uV = ((vsel * 12.5) + 600) * 1000 > + * > + * This structure stores the OPP information for a given domain. > + * Due to legacy reasons, this structure is currently exposed and > + * will soon be removed elsewhere and will only be used as a handle > + * from the OPP internal referencing mechanism > + */ > +struct omap_opp { > + bool enabled; > + unsigned long rate; > + u8 opp_id __deprecated; > + u16 vsel; > +}; > + > +/** > + * opp_get_voltage() - Gets the voltage corresponding to an opp > + * @opp: opp for which voltage has to be returned for > + * > + * Return voltage in micro volt corresponding to the opp, else > + * return 0 > + */ > +unsigned long opp_get_voltage(const struct omap_opp *opp); > + > +/** > + * opp_get_freq() - Gets the frequency corresponding to an opp > + * @opp: opp for which frequency has to be returned for > + * > + * Return frequency in hertz corresponding to the opp, else > + * return 0 > + */ > +unsigned long opp_get_freq(const struct omap_opp *opp); > + > +/** > + * opp_get_opp_count - Get number of opps enabled in the opp list > + * @num: returns the number of opps > + * @oppl: opp list > + * > + * This functions returns the number of opps if there are any OPPs enabled, > + * else returns corresponding error value. > + */ > +int opp_get_opp_count(const struct omap_opp *oppl); > + > +#define OPP_SEARCH_HIGH (0 << 1) > +#define OPP_SEARCH_LOW (1 << 1) > +/** > + * opp_find_freq_approx() - Search for an approximate freq > + * @oppl: starting list > + * @freq: start frequency > + * @dir_flags: search direction > + * OPP_SEARCH_HIGH - search for next highest freq > + * OPP_SEARCH_LOW - search for next lowest freq > + * > + * Search for the higher/lower *enabled* OPP than a starting freq > + * from a start opp list. > + > + * Returns *opp and *freq is populated with the next match, > + * else returns NULL > + * > + * Example usages: > + * * print all frequencies in descending order * > + * unsigned long freq; > + * struct omap_opp *opp; > + * for(opp = oppl, freq = ULONG_MAX; opp; > + * opp = opp_find_freq_approx(opp, &freq, OPP_SEARCH_LOW)) > + * pr_info("%ld ", freq); > + * > + * * print all frequencies in ascending order * > + * unsigned long freq = 0; > + * struct omap_opp *opp; > + * for(opp = oppl, freq = 0; opp; > + * opp = opp_find_freq_approx(opp, &freq, OPP_SEARCH_HIGH)) > + * pr_info("%ld ", freq); > + * NOTE: if we set freq as ULONG_MAX, we get the highest enabled frequency > + * > + */ > +struct omap_opp *opp_find_freq_approx(struct omap_opp *oppl, > + unsigned long *freq, u8 dir_flags); > + > +/** > + * opp_find_freq_exact() - search for an exact frequency > + * @oppl: OPP list > + * @freq: frequency to search for > + * @enabled: enabled/disabled OPP to search for > + * > + * searches for the match in the opp list and returns handle to the matching > + * opp if found, else returns NULL. > + * > + * Note enabled is a modifier for the search. if enabled=true, then the match is > + * for exact matching frequency and is enabled. if true, the match is for exact > + * frequency which is disabled. > + */ > +struct omap_opp *opp_find_freq_exact(struct omap_opp *oppl, > + unsigned long freq, bool enabled); > + > + > +/** > + * struct omap_opp_def - OMAP OPP Definition > + * @enabled: True/false - is this OPP enabled/disabled by default > + * @freq: Frequency in hertz corresponding to this OPP > + * @u_volt: Nominal voltage in microvolts corresponding to this OPP > + * > + * OMAP SOCs have a standard set of tuples consisting of frequency and voltage > + * pairs that the device will support per voltage domain. This is called > + * Operating Points or OPP. The actual definitions of OMAP Operating Points > + * varies over silicon within the same family of devices. For a specific > + * domain, you can have a set of {frequency, voltage} pairs and this is denoted > + * by an array of omap_opp_def. As the kernel boots and more information is > + * available, a set of these are activated based on the precise nature of > + * device the kernel boots up on. It is interesting to remember that each IP > + * which belongs to a voltage domain may define their own set of OPPs on top > + * of this - but this is handled by the appropriate driver. > + */ > +struct omap_opp_def { > + bool enabled; > + unsigned long freq; > + u32 u_volt; > +}; > + > +/** > + * opp_add - Add/initialize an OPP table from a table definitions > + * @oppl: Returned back to caller as the opp list to reference the OPP > + * @opp_defs: Array of omap_opp_def to describe the OPP. This list should be > + * 0 terminated. > + * > + * This function adds the opp definition to an internal opp list and returns > + * a handle representing the OPP list. This handle is then used for further > + * validation, search, modification operations on the OPP list. > + * > + * This function returns 0 and the pointer to the allocated list through oppl if > + * success, else corresponding error value. Caller should NOT free the oppl. > + * opps_defs can be freed after use. > + * > + * NOTE: caller should assume that on success, oppl is probably populated with > + * a new handle and the new handle should be used for further referencing > + */ > +int opp_add(struct omap_opp **oppl, const struct omap_opp_def *opp_defs); I'd prefer to see what has been proposed by Kevin previously. If I understood correctly, you would to split this one into two functions: opp_add - To add a single opp. At least that is what one would expect from its name. opp_init - iterate over all opps definition that need to be added and call opp_add. I'd name it 'opp_init_table' though, as opp_init sounds like initializing a single opp. > + > +/** > + * opp_enable - Enable a specific OPP > + * @opp: pointer to opp > + * > + * Enables a provided opp. If the operation is valid, this returns 0, else the > + * corresponding error value. > + * > + * OPP used here is from the the opp_is_valid/opp_has_freq or other search > + * functions > + */ > +int opp_enable(struct omap_opp *opp); > + > +/** > + * opp_disable - Disable a specific OPP > + * @opp: pointer to opp > + * > + * Disables a provided opp. If the operation is valid, this returns 0, else the > + * corresponding error value. > + * > + * OPP used here is from the the opp_is_valid/opp_has_freq or other search > + * functions > + */ > +int opp_disable(struct omap_opp *opp); > + > +#endif /* __ASM_ARM_OMAP_OPP_H * > > -- > Regards, > Nishanth Menon > -- > 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 -- Eduardo Valentin -- 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
