From: Felix Kaechele <felix@kaechele.ca>
To: Mark Brown <broonie@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Job Noorman <job@noorman.info>, Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
linux-input@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/5] input: himax_hx83112b: implement MCU register reading
Date: Tue, 14 May 2024 10:01:19 -0400 [thread overview]
Message-ID: <afab9026-e843-4cc4-8733-f45e9ab34276@kaechele.ca> (raw)
In-Reply-To: <44570cd2-9540-47f8-a409-26220b0812fb@sirena.org.uk>
On 2024-05-14 05:46, Mark Brown wrote:
> On Mon, May 13, 2024 at 04:01:59PM -0700, Dmitry Torokhov wrote:
>> On Sat, May 11, 2024 at 08:12:24AM -0400, Felix Kaechele wrote:
>>> Implement reading from the MCU in a more universal fashion. This allows
>>> properly handling reads of more than 4 bytes using the AHB FIFO
>>> implemented in the chip.
>
>> Mark, do we have anything in regmap to support this better or having a
>> wrapper is the best solution here?
>
> No, I've not seen something that explicitly requires toggling a burst
> mode on and off to do a bulk operation. Off the top of my head I'd
> suggest just always leaving the burst mode enabled but I assume there's
> some downside to doing that. We could add something but I'm not sure if
> it's worth it without having seen any other devices with the same need.
I can experiment some more with just leaving burst mode enabled.
Since the vendor driver invariably enables burst mode before any
transaction of more than 4 bytes I'll have to see if burst mode does
remain enabled under all circumstances of normal operation.
Since I don't have access to the datasheet I cannot know what the
intended behaviour and/or downsides are. Due to that I played it safe
and mimicked the behaviour of the vendor driver.
I'm guessing not having to enable burst mode on every touch event
interrupt could also mean an improvement in latency, since we save two
write cycles on the bus for each fetching of the event data.
Not sure how measurable that would be though.
I'm thinking to myself Himax at some point recognized this and that is
why we see a dedicated touch event read register on later models in this
chip family.
Regards,
Felix
next prev parent reply other threads:[~2024-05-14 14:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-11 12:12 [PATCH v2 0/5] input: himax_hx83112b: add support for HX83100A Felix Kaechele
2024-05-11 12:12 ` [PATCH v2 1/5] dt-bindings: input: touchscreen: himax,hx83112b: add HX83100A Felix Kaechele
2024-05-11 12:38 ` Conor Dooley
2024-05-11 14:10 ` Felix Kaechele
2024-05-12 12:04 ` Conor Dooley
2024-05-11 12:12 ` [PATCH v2 2/5] input: himax_hx83112b: use more descriptive register defines Felix Kaechele
2024-05-11 12:12 ` [PATCH v2 3/5] input: himax_hx83112b: implement MCU register reading Felix Kaechele
2024-05-13 23:01 ` Dmitry Torokhov
2024-05-14 9:46 ` Mark Brown
2024-05-14 14:01 ` Felix Kaechele [this message]
2024-05-29 23:07 ` Felix Kaechele
2024-05-11 12:12 ` [PATCH v2 4/5] input: himax_hx83112b: add himax_chip struct for multi-chip support Felix Kaechele
2024-05-11 12:12 ` [PATCH v2 5/5] input: himax_hx83112b: add support for HX83100A Felix Kaechele
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