Re: [PATCH 2/4] soc: apple: rtkit: Implement OSLog buffers properly

[Alyssa Rosenzweig <alyssa@rosenzweig.io>]

> +	if (ep == APPLE_RTKIT_EP_OSLOG) {
> +		buffer->size = FIELD_GET(APPLE_RTKIT_OSLOG_SIZE, msg);
> +		buffer->iova = FIELD_GET(APPLE_RTKIT_OSLOG_IOVA, msg) << 12;
> +	} else {
> +		buffer->size = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_SIZE, msg) << 12;
> +		buffer->iova = FIELD_GET(APPLE_RTKIT_BUFFER_REQUEST_IOVA, msg);
> +	}

The shifts are suspiciously asymmetric. Are we really sure this is
correct? My guess is that both size & iova for both oslog & buffer need
to be page-aligned, so all 4 lines should be shifted, and the bit
offsets should be adjusted in turn, and the lower 12-bits in oslog_size
and buffer_iova are reserved. But that's just a guess.

Anyway if this logic is really what we want it deserves a comment
because it looks like a typo.

(Likewise later in the patch)