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From: Krzysztof Kozlowski <krzk@kernel.org>
To: Alex Lanzano <lanzano.alex@gmail.com>
Cc: mehdi.djait@bootlin.com,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: display: Add Sharp Memory LCD bindings
Date: Sun, 28 Jul 2024 16:43:42 +0200	[thread overview]
Message-ID: <8edc9bd6-2130-44aa-aeaf-cfb5ca43ca0f@kernel.org> (raw)
In-Reply-To: <ko6kavj46gm5py3vtfnt6zdka5ar2zigmpg72kt4zr6f3tbhwr@nbbhn726oo36>

On 28/07/2024 14:56, Alex Lanzano wrote:
>>>>> +
>>>>> +  spi-cs-high: true
>>>>
>>>> You can drop it.
>>>>
>>>
>>> This is a required property in order for the display to function correctly.
>>> But I have no issues removing it if there's a better place to document it.
>>
>> The sharp LCD device or the board (e.g. via some inversion)?
>>
> 
> The sharp LCD device itself.
> 
> https://cdn.sparkfun.com/assets/d/e/8/9/7/LS013B7DH03_datasheet.pdf
> Page 16 of the PDF below shows the timing chart for it if interested

OK, so you enforce chip select as always high and then someone comes
with a board which has a inversion and expect the SoC to drive it low,
as usually? In such system this would not work, would it?

IOW, I think this is the first case where you require specific CS high
and this should make you think why...

Best regards,
Krzysztof


  reply	other threads:[~2024-07-28 14:43 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-25  0:47 [PATCH 0/2] Add driver for Sharp Memory LCD Alex Lanzano
2024-07-25  0:47 ` [PATCH 1/2] dt-bindings: display: Add Sharp Memory LCD bindings Alex Lanzano
2024-07-25  6:17   ` Krzysztof Kozlowski
2024-07-26  0:33     ` Alex Lanzano
2024-07-27 16:30     ` Alex Lanzano
2024-07-28  8:40       ` Krzysztof Kozlowski
2024-07-28 12:56         ` Alex Lanzano
2024-07-28 14:43           ` Krzysztof Kozlowski [this message]
2024-07-28 14:52             ` Alex Lanzano
2024-07-25  6:18   ` Krzysztof Kozlowski
2024-07-26  0:36     ` Alex Lanzano
2024-07-25  0:47 ` [PATCH 2/2] drm/tiny: Add driver for Sharp Memory LCD Alex Lanzano
2024-07-25  5:20   ` Christophe JAILLET
2024-07-25  6:08   ` Krzysztof Kozlowski
2024-07-26  1:25     ` Alex Lanzano
2024-07-26  8:43       ` Krzysztof Kozlowski
2024-07-25  5:45 ` [PATCH 0/2] " Thomas Petazzoni
2024-07-26  0:07   ` Alex Lanzano
2024-07-26  6:27     ` Thomas Petazzoni
2024-07-26 19:44 ` [PATCH v2 " Alex Lanzano
2024-07-26 19:44   ` [PATCH v2 1/2] dt-bindings: display: Add Sharp Memory LCD bindings Alex Lanzano
2024-07-27  9:06     ` Krzysztof Kozlowski
2024-07-27 18:54       ` Alex Lanzano
2024-07-26 19:44   ` [PATCH v2 2/2] drm/tiny: Add driver for Sharp Memory LCD Alex Lanzano
2024-07-26 22:00     ` kernel test robot
2024-07-26 22:12     ` Christophe JAILLET
2024-07-27  4:53       ` Alex Lanzano
2024-07-27  9:03     ` Krzysztof Kozlowski
2024-07-27 17:45       ` Alex Lanzano
2024-07-27  9:00   ` [PATCH v2 0/2] " Krzysztof Kozlowski
2024-07-27 17:26     ` Alex Lanzano

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