On Tue, Jun 7, 2011 at 20:12, Colin Cross <[email protected]> wrote:
>> Bootloaders should in theory setup a frequency which is enabled in
>> OPP table. However, there can be mismatches, and we should try
>> both going lower in addition to the going higher to find
>> a match if bootloader boots up at a OPP than the kernel thinks it
>> should be allowed. We also sequence the frequency and voltage settings
>> properly.
>>
>> Reported-by: Colin Cross <[email protected]>
>> Signed-off-by: Nishanth Menon <[email protected]>
>> ---
>> PS: Apologies on the spam.. for some reason 10/10 never appeared in
>> http://marc.info/?l=linux-omap&r=2&b=201106&w=2 - grumble grumble :(
>>
>> arch/arm/mach-omap2/pm.c | 55
>> ++++++++++++++++++++++++++++++++++++---------
>> 1 files changed, 44 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
>> index 7355347..ce7554b 100644
>> --- a/arch/arm/mach-omap2/pm.c
>> +++ b/arch/arm/mach-omap2/pm.c
>> @@ -174,7 +174,9 @@ static int __init omap2_set_init_voltage(char *vdd_name,
>> ch ar *clk_name,
>> struct voltagedomain *voltdm;
>> struct clk *clk;
>> struct opp *opp;
>> - unsigned long freq, bootup_volt;
>> + unsigned long freq_cur, freq_valid, bootup_volt;
>> + int raise_freq_idx, i;
>> + int ret = -EINVAL;
>>
>> if (!vdd_name || !clk_name || !dev) {
>> printk(KERN_ERR "%s: Invalid parameters!\n", __func__);
>> @@ -195,16 +197,20 @@ static int __init omap2_set_init_voltage(char
>> *vdd_name, char *clk_name,
>> goto exit;
>> }
>>
>> - freq = clk->rate;
>> - clk_put(clk);
>> + freq_cur = clk->rate;
>> + freq_valid = freq_cur;
>>
>> rcu_read_lock();
>> - opp = opp_find_freq_ceil(dev, &freq);
>> + opp = opp_find_freq_ceil(dev, &freq_valid);
>> if (IS_ERR(opp)) {
>> - rcu_read_unlock();
>> - printk(KERN_ERR "%s: unable to find boot up OPP for vdd_%s\n",
>> - __func__, vdd_name);
>> - goto exit;
>> + opp = opp_find_freq_floor(dev, &freq_valid);
>> + if (IS_ERR(opp)) {
>> + rcu_read_unlock();
>> + pr_err("%s: no boot OPP match for %ld on vdd_%s\n",
>> + __func__, freq_cur, vdd_name);
>> + ret = -ENOENT;
>> + goto exit_ck;
>> + }
>> }
>>
>> bootup_volt = opp_get_voltage(opp);
>> @@ -212,11 +218,38 @@ static int __init omap2_set_init_voltage(char
>> *vdd_name, char *clk_name,
>> if (!bootup_volt) {
>> printk(KERN_ERR "%s: unable to find voltage corresponding"
>> "to the bootup OPP for vdd_%s\n", __func__, vdd_name);
>> - goto exit;
>> + ret = -ENOENT;
>> + goto exit_ck;
>> }
>>
>> - voltdm_scale(voltdm, bootup_volt);
>> - return 0;
>> + /*
>> + * Frequency and Voltage have to be sequenced: if we move from
>> + * a lower frequency to higher frequency, raise voltage, followed by
>> + * frequency, and vice versa. we assume that the voltage at boot
>> + * is the required voltage for the frequency it was set for.
>> + */
>> + raise_freq_idx = freq_cur < freq_valid;
>> + for (i = 0; i < 2; i++) {
>> + if (i == raise_freq_idx)
>> + ret = clk_set_rate(clk, freq_valid);
>> + else
>> + ret = voltdm_scale(voltdm, bootup_volt);
>> + if (ret < 0) {
>> + pr_err("%s: unable to set %s-%s(f=%ld v=%ld)on
>> vdd%s\n",
>> + __func__,
>> + (i == raise_freq_idx) ? "clk" : "voltage",
>> + (i == raise_freq_idx) ? clk_name : vdd_name,
>> + freq_valid, bootup_volt, vdd_name);
>> + goto exit_ck;
>> + }
>> + }
>
> This is way too complicated. Writing out what you mean is much more
> readable, and not many more LOC:
hmm.. fine with me..
>
> if (freq_cur < freq_valid) {
> ret = voltdm_scale(voltdm, bootup_volt);
> if (ret) {
> pr_err("%s: unable to set voltage-%s(f=%ld v=%ld)on vdd%s\n",
> vdd_name, freq_valid, bootup_volt, vdd_name);
> goto exit_ck;
> }
> }
>
optionally -
if (freq_cur == freq_valid) {
> ret = clk_set_rate(clk, freq_valid);
> if (ret) {
> pr_err("%s: unable to set clk-%s(f=%ld v=%ld)on vdd%s\n",
> clk_name, freq_valid, bootup_volt, vdd_name);
> goto exit_ck;
> }
}
>
> if (freq_cur > freq_valid) {
since we dont really know how the bootloader might have set the
voltage, (twl4030 allows i2c1 programming, others plugged on I2C_SR
can either use forcedupdate/vc bypass, we should do a force setting of
voltage..
if (freq_cur >= freq_valid) ?
> ret = voltdm_scale(voltdm, bootup_volt);
> if (ret) {
> pr_err("%s: unable to set voltage-%s(f=%ld v=%ld)on vdd%s\n",
> vdd_name, freq_valid, bootup_volt, vdd_name);
> goto exit_ck;
> }
> }
>
>> +
>> + ret = 0;
>> +exit_ck:
>> + clk_put(clk);
>> +
>> + if (!ret)
>> + return 0;
>>
>> exit:
>> printk(KERN_ERR "%s: Unable to put vdd_%s to its init voltage\n\n",
>> --
>> 1.7.1
>>
>> --
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>
Regards,
Nishanth Menon
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