Hi Mark,
Thank you for review.
On 9/3/2021 11:43 PM, Mark Brown wrote:
On Fri, Aug 27, 2021 at 03:03:52PM +0530, Sameer Pujar wrote:
The Master Volume Control (MVC) provides gain or attenuation to a digital signal path. It can be used in input or output signal path for per-stream volume control or it can be used as master volume control. The MVC block has one input and one output. The input digital stream can be mono or multi-channel (up to 7.1 channels) stream. An independent mute control is also included in the MVC block.
Looks like it's also got a little bit of other DSP in there (a simple EQ?). Not that it really matters.
MVC does not have EQ block. In fact it is part of another processing module, the driver for which is not part of this series.
- if (reg == TEGRA210_MVC_CTRL) {
u32 val;u8 mute_mask;- } else {
u8 chan = (reg - TEGRA210_MVC_TARGET_VOL) / REG_SIZE;s32 val = mvc->volume[chan];It's not clear to me why we're using the same callbacks for the volume and mute settings - there's no shared code on the read path and only a tiny bit on the write path.
The volume switch trigger is common in put(). The get() is probably influenced from the put() and common function is maintained. If it makes more clear I will separate these out.
- err |= regmap_update_bits(mvc->regmap, TEGRA210_MVC_SWITCH,
TEGRA210_MVC_VOLUME_SWITCH_MASK,TEGRA210_MVC_VOLUME_SWITCH_TRIGGER);+end:
- pm_runtime_put(cmpnt->dev);
- return err;
+}
_put() should return 0 if there's no change or 1 for a change.
done
- /* SW reset */
- regmap_write(mvc->regmap, TEGRA210_MVC_SOFT_RESET, 1);
What about all the cached values in the regmap, won't they get out of sync? Especially things like volume and mute, it looks like the mute just gets written directly to the regmap and not otherwise saved.
1. I think original idea was to disable MVC (forcefully) before new configurations are applied and eventually it gets enabled via DAPM path. DAPM path handles disable also, but sometimes MVC may get stuck in enable state (due to a previous usage) when all the data in pipeline is not processed. My understanding is that reset is restricted to this alone. The volume/mute registers seem not to be affected by reset. However I will confirm with HW about the reset behavior and affected register map. Thanks for pointing this.
2. The mute is part of volatile register and volume is not. If the system is muted and any volume settings are made, the system is unmuted automatically. For this reason mute is always read from HW. For volume it is saved for local computation.