Re: [PATCH v4 1/1] regmap: Synchronize cache for the page selector

[Andy Shevchenko]

On Wed, Feb 18, 2026 at 11:50:03AM +0100, Marek Szyprowski wrote:
> On 18.02.2026 10:57, Andy Shevchenko wrote:
> > On Wed, Feb 18, 2026 at 09:30:41AM +0100, Marek Szyprowski wrote:
> >> On 18.02.2026 08:46, Andy Shevchenko wrote:

...

> >>> ---
> >>> v4: reworked the approach completely
> >>>
> >>> Marek, Dmitry,
> >>> Please, test on your HW to be sure this will have no side effects
> >>> in your case with LT9611.
> >> It looks that it ends in infinite recurrent calls after this patch:
> > Thank you for the prompt testing! Can you also _add_ the patch on top from
> > https://lore.kernel.org/all/Z4ppo8wV3nicOfAQ@xxxxxxxxxxxxxxxxxx/ ?
> 
> I've applied that change and the driver fails with the following messages:

At least I see that nothing changed in the LT9611 driver.

> # dmesg | grep lt96
> lt9611uxc 5-002b: LT9611 revision: 0x00.00.00
> lt9611uxc 5-002b: LT9611 version: 0x00
> lt9611uxc 5-002b: FW version 0, enforcing firmware update
> lt9611uxc 5-002b: Direct firmware load for lt9611uxc_fw.bin failed with 
> error -2
> lt9611uxc 5-002b: probe with driver lt9611uxc failed with error -2
> 
> Maybe this driver simply doesn't use this regmap feature properly and 
> there is no point trying to fix regmap?

regmap definitely missed that detail, needs to be fixed, but the driver
for sure abuses the regmap ranges.

Okay, thank you very much for testing (it's a pity I have no such HW
to test the driver, I will think more about lt9611 driver and next time
come up with something done there as well).

> >> Insufficient stack space to handle exception!
> >> ESR: 0x0000000096000047 -- DABT (current EL)
> >> FAR: 0xffff8000859bffe0
> >> Task stack:     [0xffff8000859c0000..0xffff8000859c4000]
> >> IRQ stack:      [0xffff800080030000..0xffff800080034000]
> >> Overflow stack: [0xffff0001fef36140..0xffff0001fef37140]
> >> CPU: 6 UID: 0 PID: 341 Comm: (udev-worker) Not tainted
> >> 6.19.0-next-20260217+ #12215 PREEMPT
> >> Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
> >> pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> >> pc : _regmap_select_page+0x4/0x120
> >> lr : _regmap_raw_read+0x240/0x340

-- 
With Best Regards,
Andy Shevchenko