DRM Driver implementation question

Yoshihiro Shimoda yoshihiro.shimoda.uh at renesas.com
Tue Sep 17 04:38:58 UTC 2019

Hi Gareth,

> From: Gareth Williams, Sent: Monday, September 16, 2019 10:56 PM
> Hi Laurent/Kieran,
> I need to upstream a driver for a display controller that within its registers memory region contains registers related
> to a PWM device. The PWM device is for controlling the backlight of the display.
> Ideally, I would like to create a separated driver for the PWM, so that I can re-use "pwm-backlight", but since the registers
> for the PWM are right in the middle of the registers for the display controller I would need to ioremap the memory region
> for the PWM registers region twice, once from the display controller driver, and once from the PWM driver.
> Do you think that the double ioremap would be acceptable upstream?

I think that an MFD driver can support such hardware. I checked Documentation/devicetree/bindings/mfd roughly,
and then atmel-hlcdc.txt seems to have a display controller and a PWM device.

Best regards,
Yoshihiro Shimoda

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