lkml.org 
[lkml]   [2014]   [Apr]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] ASoC: DAPM: Add support for multi register mux
    On 04/02/2014 08:56 AM, Songhee Baek wrote:
    >
    >
    >> -----Original Message-----
    >> From: Lars-Peter Clausen [mailto:lars@metafoo.de]
    >> Sent: Tuesday, April 01, 2014 11:47 PM
    >> To: Songhee Baek
    >> Cc: Arun Shamanna Lakshmi; lgirdwood@gmail.com; broonie@kernel.org;
    >> swarren@wwwdotorg.org; perex@perex.cz; tiwai@suse.de; alsa-
    >> devel@alsa-project.org; linux-kernel@vger.kernel.org
    >> Subject: Re: [PATCH] ASoC: DAPM: Add support for multi register mux
    >>
    >> On 04/02/2014 08:17 AM, Songhee Baek wrote:
    >>>> -----Original Message-----
    >>>> From: Lars-Peter Clausen [mailto:lars@metafoo.de]
    >>>> Sent: Tuesday, April 01, 2014 11:00 PM
    >>>> To: Arun Shamanna Lakshmi
    >>>> Cc: lgirdwood@gmail.com; broonie@kernel.org;
    >> swarren@wwwdotorg.org;
    >>>> perex@perex.cz; tiwai@suse.de; alsa-devel@alsa-project.org; linux-
    >>>> kernel@vger.kernel.org; Songhee Baek
    >>>> Subject: Re: [PATCH] ASoC: DAPM: Add support for multi register mux
    >>>>
    >>>> On 04/01/2014 08:26 PM, Arun Shamanna Lakshmi wrote:
    >>>> [...]
    >>>>>>> diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index
    >>>>>>> c8a780d..4d2b35c 100644
    >>>>>>> --- a/sound/soc/soc-dapm.c
    >>>>>>> +++ b/sound/soc/soc-dapm.c
    >>>>>>> @@ -514,9 +514,9 @@ static int dapm_connect_mux(struct
    >>>>>> snd_soc_dapm_context *dapm,
    >>>>>>> unsigned int val, item;
    >>>>>>> int i;
    >>>>>>>
    >>>>>>> - if (e->reg != SND_SOC_NOPM) {
    >>>>>>> - soc_widget_read(dest, e->reg, &val);
    >>>>>>> - val = (val >> e->shift_l) & e->mask;
    >>>>>>> + if (e->reg[0] != SND_SOC_NOPM) {
    >>>>>>> + soc_widget_read(dest, e->reg[0], &val);
    >>>>>>> + val = (val >> e->shift_l) & e->mask[0];
    >>>>>>> item = snd_soc_enum_val_to_item(e, val);
    >>>>>>
    >>>>>> This probably should handle the new enum type as well. You'll
    >>>>>> probably need some kind of flag in the struct to distinguish
    >>>>>> between the two enum types.
    >>>>>
    >>>>> Any suggestion on the flag name ?
    >>>>>
    >>>>
    >>>> How about 'onehot'?
    >>>>
    >>>> [...]
    >>>>>>> + reg_val = BIT(bit_pos);
    >>>>>>> + }
    >>>>>>> +
    >>>>>>> + for (i = 0; i < e->num_regs; i++) {
    >>>>>>> + if (i == reg_idx) {
    >>>>>>> + change = snd_soc_test_bits(codec, e->reg[i],
    >>>>>>> + e->mask[i],
    >>>>>> reg_val);
    >>>>>>> +
    >>>>>>> + } else {
    >>>>>>> + /* accumulate the change to update the
    >> DAPM
    >>>>>> path
    >>>>>>> + when none is selected */
    >>>>>>> + change += snd_soc_test_bits(codec, e-
    >>> reg[i],
    >>>>>>> + e->mask[i], 0);
    >>>>>>
    >>>>>> change |=
    >>>>>>
    >>>>>>> +
    >>>>>>> + /* clear the register when not selected */
    >>>>>>> + snd_soc_write(codec, e->reg[i], 0);
    >>>>>>
    >>>>>> I think this should happen as part of the DAPM update sequence like
    >>>>>> you had earlier. Some special care should probably be take to make
    >>>>>> sure that you de-select the previous mux input before selecting the
    >>>>>> new one if the new one is in a different register than the previous one.
    >>>>>
    >>>>> I am not sure I follow this part. We are clearing the 'not selected'
    >>>>> registers before we set the one we want. Do you want us to loop the
    >>>>> logic of soc_dapm_mux_update_power for each register ? or do you
    >>>>> want to change the dapm_update structure so that it takes all the
    >>>>> regs, masks, and values together ?
    >>>>
    >>>> The idea with the dapm_update struct is that the register updates are
    >>>> done in the middle of the power-down and power-up sequence. So yes,
    >>>> change the dapm_update struct to be able to hold all register updates
    >>>> and do all register updates in dapm_widget_update. I think an earlier
    >>>> version of your patch already had this.
    >>>
    >>> Is the change similar to as shown below?
    >>>
    >>> for (reg_idx = 0; reg_idx < e->num_regs; reg_idx++) {
    >>> val = e->values[item * e->num_regs + reg_idx];
    >>> ret = snd_soc_update_bits_locked(codec, e->reg[reg_idx],
    >>> e->mask[reg_idx], val);
    >>> if (ret)
    >>> return ret;
    >>> }
    >>>
    >>> During updating of the register's value, the above change can create
    >>> non-zero value in two different registers (very short transition) as
    >>> Mark mentioned for that change so we need to clear register first
    >>> before writing the desired value in the register.
    >>>
    >>> Should we add the clearing all registers and write the mux value in
    >>> desired register in the update function?
    >>>
    >>
    >> In dapm_update_widget() you have this line:
    >>
    >> ret = soc_widget_update_bits(w, update->reg, update->mask, update-
    >>> val);
    >>
    >> That needs to be done for every register update. When you setup the
    >> update struct you need to make sure that the register clears come before
    >> the register set.
    >>
    >> E.g. if you have register 0x3, 0x4, 0x5 and you select a bit in register 0x4 it
    >> should look like this.
    >>
    >> update->reg[0] = 0x3;
    >> update->val[0] = 0x0;
    >> update->reg[1] = 0x5;
    >> update->val[1] = 0x0;
    >> update->reg[2] = 0x4;
    >> update->val[2] = 0x8;
    >>
    >> When you set a bit in register 0x3 it should look like this:
    >>
    >> update->reg[0] = 0x4;
    >> update->val[0] = 0x0;
    >> update->reg[1] = 0x5;
    >> update->val[1] = 0x0;
    >> update->reg[2] = 0x3;
    >> update->val[2] = 0x1;
    >>
    >> So basically the write operation goes into update->reg[e->num_regs-1] the
    >> clear operations go into the other slots before that.
    >
    > Does update reg/val array have the writing sequence, is it correct?
    > And can I assume that update struct has reg/val/mask arrays not pointers?

    Right now the update struct does not have support for multiple register
    writes. That's up to you to implement this. I guess making it an array for
    now should be fine. But you need to add some safety checks to make sure that
    num_regs is not larger or equal to the array size.



    \
     
     \ /
      Last update: 2014-04-02 09:21    [W:6.210 / U:0.164 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site