Re: [alsa-devel] [PATCH 1/2] regmap: cache: Fix regcache_sync_block for non-autoincrementing devices

From: Jarkko Nikula
Date: Wed Aug 27 2014 - 01:52:28 EST

On 08/26/2014 05:21 PM, Takashi Iwai wrote:
At Tue, 26 Aug 2014 17:03:12 +0300,
Jarkko Nikula wrote:
Commit 75a5f89f635c ("regmap: cache: Write consecutive registers in a single
block write") expected that autoincrementing writes are supported if
hardware has a register format which can support raw writes.

This is not necessarily true and thus for instance rbtree sync can fail when
there is need to sync multiple consecutive registers but block write to
device fails due not supported autoincrementing writes.

Fix this by spliting raw block sync to series of single register writes for
devices that don't support autoincrementing writes.
Wouldn't it suffice to correct regmap_can_raw_write() to return false
if map->use_single_rw is set?

I don't know. I was thinking that also but was unsure about it since regcache_sync_block_raw() and regcache_sync_block_single() code paths use different regmap write functions. regcache_sync_block_raw() ends up calling _regmap_raw_write() which takes care of page select operation when needed and regcache_sync_block_single() uses _regmap_write() which doesn't.

Which makes me thinking should the regcache_sync_block_single() also use _regmap_raw_write() in order to take care of page selects?

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