Re: [PATCH RFC 1/2] dt-bindings: regmap: add common schema for no-sequential-read

[Richard Leitner]

Hi Mark,

thanks the quick feedback.

On Wed, Jul 22, 2026 at 02:59:12PM +0100, Mark Brown wrote:
> On Wed, Jul 22, 2026 at 10:42:46AM +0200, Richard Leitner wrote:
> > Introduce a common regmap dt-binding schema with an optional boolean
> > property no-sequential-read to describe hardware integrations where
> > reading multiple consecutive registers in a single operation is not
> > reliable and registers must be read individually.
> 
> > A typical case are imaging sensors used on vendor-provided camera
> > modules whose bus integration does not support reads that advance across
> > consecutive register addresses. In such cases, single-register reads
> > work, but bulk reads do not. This restriction is a property of the
> > concrete hardware integration, not of the chip itself. It therefore
> > cannot be identified from the device driver and duplicating firmware
> > parsing in each affected driver does not scale.
> 
> No, this should not be a DT property.  We should discover this through
> the bus, just like we do currently for the various I2C quirks that are
> advertied by the I2C subsystem.

What do you mean "discover this through the bus"? As mentioned in the
commit message there is no possibility to detect that within the affected
I2C device drivers.

Or do you mean that it should be "discovered" by modelling the MCU which
"proxies" the I2C traffic between the host and the sensor/device as some
kind of "parent" device of the sensor?

Or something other?

Sorry, if I don't get it, but currently I see no other option than
providing this information somehow via device-tree. No matter if it's in
regmap or I2C.

thanks & regards;rl