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From: "Noralf Trønnes" <noralf@tronnes.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Felipe Balbi <balbi@kernel.org>, Mark Brown <broonie@kernel.org>,
	Lee Jones <lee.jones@linaro.org>, USB <linux-usb@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: [RFC 0/9] Regmap over USB for Multifunction USB Device (gpio, display, ...)
Date: Tue, 18 Feb 2020 22:31:02 +0100	[thread overview]
Message-ID: <cda21859-0bd2-2a7f-c74a-360ef7aabadb@tronnes.org> (raw)
In-Reply-To: <CAHp75Vc6=V=cXM0mmh88V6XLmJT6kFnJCS547vgxX0zBG+cTZQ@mail.gmail.com>



Den 18.02.2020 21.57, skrev Andy Shevchenko:
> On Sun, Feb 16, 2020 at 7:30 PM Noralf Trønnes <noralf@tronnes.org> wrote:
>>
>> Hi,
>>
>> A while back I had the idea to turn a Raspberry Pi Zero into a $5
>> USB to HDMI/SDTV/DSI/DPI display adapter.
>>
>> Thinking about how to represent the display to the driver I realised
>> that hardware use registers as API. And Linux does have a generic
>> register abstraction: regmap. Furthermore this means that if I can do a
>> regmap over USB implementation, it will be easy to do other functions
>> like gpio, adc and others. After a few iterations trying to understand
>> the USB subsystem and satisfying driver requirements, I now have
>> something that looks promising.
>>
>> I'm sending out an early version hoping to get feedback especially on
>> the core parts that handles regmap and interrupts.
>>
>> Overview:
>>
>>           USB Host          :         USB Device
>>                             :
>>             --------------  :  ------------------
>> ----------  | mfd: mud   |  :  | f_mud          |  ----------
>> | Driver |  --------------  :  |                |  | Driver |
>> ----------  | regmap-usb |  :  | (mud_regmap)   |  ----------
>>             --------------  :  ------------------
>>
>>
>> I've attached 2 drivers:
>> - gpio/pinctrl: is more or less finished
>> - display: needs a lot more work
> 
> Can regmap-usb be used for drivers/mfd/dln2.c for example?
> 

No, apparently dln-2 uses custom protocol structs for each function with
a common header. regmap-usb is a register abstraction with the ability
to bulk read/write multiple registers in one transfer.

I see that dln-2 does a lot of what I'm aiming for except that it
doesn't have the display part.

Noralf.
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      reply	other threads:[~2020-02-18 21:31 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-16 17:21 [RFC 0/9] Regmap over USB for Multifunction USB Device (gpio, display, ...) Noralf Trønnes
2020-02-16 17:21 ` [RFC 1/9] regmap: Add USB support Noralf Trønnes
2020-02-17 12:11   ` Mark Brown
2020-02-17 21:33     ` Noralf Trønnes
2020-02-17 21:39       ` Mark Brown
2020-02-17 22:15         ` Noralf Trønnes
2020-02-17 22:44           ` Mark Brown
2020-02-16 17:21 ` [RFC 2/9] mfd: Add driver for Multifunction USB Device Noralf Trønnes
2020-02-27  9:09   ` Lee Jones
2020-02-29 13:26     ` Noralf Trønnes
2020-02-29 16:02       ` Alan Stern
2020-02-16 17:21 ` [RFC 3/9] usb: gadget: function: Add Multifunction USB Device support Noralf Trønnes
2020-02-16 17:21 ` [RFC 4/9] pinctrl: Add Multifunction USB Device pinctrl driver Noralf Trønnes
2020-02-16 17:21 ` [RFC 5/9] usb: gadget: function: mud: Add gpio support Noralf Trønnes
2020-02-16 17:21 ` [RFC 6/9] regmap: Speed up _regmap_raw_write_impl() for large buffers Noralf Trønnes
2020-02-17 12:15   ` Mark Brown
2020-02-16 17:21 ` [RFC 7/9] drm: Add Multifunction USB Device display driver Noralf Trønnes
2020-02-16 17:21 ` [RFC 8/9] drm/client: Add drm_client_init_from_id() and drm_client_modeset_set() Noralf Trønnes
2020-02-17  9:38   ` Daniel Vetter
2020-02-23 17:43     ` Noralf Trønnes
2020-02-23 20:59       ` Daniel Vetter
2020-02-16 17:21 ` [RFC 9/9] usb: gadget: function: mud: Add display support Noralf Trønnes
2020-02-17  9:40 ` [RFC 0/9] Regmap over USB for Multifunction USB Device (gpio, display, ...) Daniel Vetter
2020-02-17 10:32 ` Neil Armstrong
2020-02-17 14:05   ` Noralf Trønnes
2020-02-18 20:57 ` Andy Shevchenko
2020-02-18 21:31   ` Noralf Trønnes [this message]

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