Re: [PATCH 1/2] regmap: Allow installing custom reg_update_bits function

From: Mark Brown
Date: Fri Oct 02 2015 - 13:19:20 EST


On Thu, Oct 01, 2015 at 08:29:19AM -0400, Jon Ringle wrote:
> On Thu, 1 Oct 2015, Mark Brown wrote:

> > This completely bypasses and therefore breaks the cache infrastructure.

> Right after sending the v2 patch, I realized that calling the
> custom reg_update_bits would only be applicable for registers that are
> marked as volatile. Would the following solution be acceptable (it would

Well, it should still *work* with a cache, though it's certainly true
that it's unlikely to have any performance benefit with cached register
since the read part of the read/modify/write cycle is essentially free
with the cache.

> also simplify the regmap_update_bits in the encx24j600 driver):

> if (regmap_volatile(map, reg) && map->reg_update_bits) {
> return map->reg_update_bits(map->bus_context, reg, mask,
> val, change, force_write);

> The cache state should not matter for volatile registers, right?

Right. I see you've sent a new patch already, I'll reply to that after
I've thought about it a little.

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