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From: Marek Vasut <marex@denx.de>
To: Frieder Schrempf <frieder.schrempf@kontron.de>,
	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Alexander Stein <alexander.stein@ew.tq-group.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Rob Herring <robh+dt@kernel.org>,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: drm/bridge: ti-sn65dsi83: Add enable delay property
Date: Mon, 12 Dec 2022 13:50:59 +0100	[thread overview]
Message-ID: <e45f363b-91e8-908e-aa2c-0b75fe5e25d4@denx.de> (raw)
In-Reply-To: <8dc209df-8b69-d4a5-a056-b5aacdf41a14@kontron.de>

On 12/12/22 13:29, Frieder Schrempf wrote:
> On 12.12.22 10:23, Krzysztof Kozlowski wrote:
>> On 12/12/2022 10:09, Frieder Schrempf wrote:
>>>>>> This does seem like a hardware bug right there, can you double-check
>>>>>> this with the hardware engineer ?
>>>>>
>>>>> Yep, checked with hardware engineer. An 470nF is attached, together
>>>>> with an
>>>>> open drain output and only the internal pull-up. So yes ~113ms rising
>>>>> time
>>>>> until 0.7 x VCC.
>>>>
>>>> I don't suppose you can have that capacitor reduced or better yet, some
>>>> external pull up added, can you ?
>>>
>>> Actually our HW engineers have implemented a similar RC circuit to
>>> provide a hardware delay for the EN signal. I think this is due to a
>>> design note in the datasheet (see chapter 7.4.1) and therefore it's
>>> probably widely spread.
>>
>> If I read section 7.4.1 correctly, it would be enough to just add delay
>> Ten=1ms instead of the capacitor, right? And that would be
>> device-specific. But if one chooses the capacitor solution, it becomes
>> now board specific.
> 
> Yes, seems like that's the case.

Can you still fix the board instead ? It would even save you on BOM.

  reply	other threads:[~2022-12-12 13:24 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-09  8:33 [PATCH 0/2] TI SN65DSI83 GPIO enable delay support Alexander Stein
2022-12-09  8:33 ` [PATCH 1/2] dt-bindings: drm/bridge: ti-sn65dsi83: Add enable delay property Alexander Stein
2022-12-09  8:39   ` Krzysztof Kozlowski
2022-12-09  8:54     ` Alexander Stein
2022-12-09  9:07       ` Krzysztof Kozlowski
2022-12-09  9:36         ` Alexander Stein
2022-12-09  9:50           ` Krzysztof Kozlowski
2022-12-09  9:51             ` Krzysztof Kozlowski
2022-12-09 12:02           ` Marek Vasut
2022-12-09 12:10             ` Krzysztof Kozlowski
2022-12-09 12:23               ` Alexander Stein
2022-12-09 12:21             ` Alexander Stein
2022-12-09 12:43               ` Marek Vasut
2022-12-09 13:38                 ` Alexander Stein
2022-12-09 14:49                   ` Marek Vasut
2022-12-12  9:09                     ` Frieder Schrempf
2022-12-12  9:23                       ` Krzysztof Kozlowski
2022-12-12 12:29                         ` Frieder Schrempf
2022-12-12 12:50                           ` Marek Vasut [this message]
2022-12-12  9:32                       ` Laurent Pinchart
2022-12-12 11:49                         ` Frieder Schrempf
2022-12-12 12:05                           ` Laurent Pinchart
2022-12-11 18:50               ` Laurent Pinchart
2022-12-09  8:33 ` [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add enable delay support Alexander Stein

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