Re: Using regmap_update_bits to update a write only register

From: Lars-Peter Clausen
Date: Sat Mar 07 2015 - 11:07:43 EST


On 03/06/2015 08:48 PM, Daniel Baluta wrote:
On Fri, Mar 6, 2015 at 7:36 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
On 03/06/2015 06:26 PM, Daniel Baluta wrote:
[...]

I can reproduce the problem with:

static struct reg_default xxx_reg_defaults[] = {
{ XXX_REG_CTRL0, 0x00 },
{ XXX_REG_CTRL1, 0x00 },
{ XXX_REG_STATUS, 0x00 },
};

but, not if the reg default definition is:

static struct reg_default xxx_reg_defaults[] = {
{ XXX_REG_STATUS, 0x00 },
{ XXX_REG_CTRL0, 0x00 },
{ XXX_REG_CTRL1, 0x00 },
};

Is this normal?


That's a rhetorical question, right?

It might be that there is a bug when growing a rbblock to the left. It
probably went unnoticed because everybody has their reg defaults ordered in
ascending order.

Try to put a few debug printks into regcache_rbtree_write() and
regcache_rbtree_insert_to_block() to see what exactly is going on when a new
register is inserted into the block. How do base_reg and top_reg change.

I cannot test is right now because I don't have access to the physical device.
Is there a way to use to test the regmap API without an I2C/SPI device?

I did some quick testing today, and the resizing the present bitmap definitely broken with the current code. Patch will follow shortly.

- Lars

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