From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BF58F149E13 for ; Thu, 3 Oct 2024 14:53:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727967206; cv=none; b=Z+PEOhX34OhHYzghAcYa5DZBFf676Iykj7FWYcypOu6BP8RBisiUpN0OJ9m2N4DMveDYph/tVysiGOHWBc6ty3FCPeXWkJ1oYlL67AnEABAd/tmwcQ+X1xz6elOYzP0mO1DsO7Bzg8qlm1N6RlP1HeE6mdefcAaXTw0vCR4ajlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727967206; c=relaxed/simple; bh=9lc2kPY0ULQSSlK35i222Zj99eDgQlTTkFCQ2NnmQd8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MEVs3uuRbJ9L48ECP6J/cjE/DquRiTKktZtOFLp9UerX0qiX7oUi82dbr6tbJEDm7MsPihZueh9WQRXJ+uDEN1ptXEIuqNks0fAQaXirlOiN65iJb5B/hhg5egPSnv+fD7CNgvAZonJSnL7KqfOgFJQ8hXfhXfREidPI9oCUNNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=hDBZlOYu; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="hDBZlOYu" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1727967201; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k0KagNPwCCq2CvCaJVY5j4td7R7+u7bJKeN0d8+4kuQ=; b=hDBZlOYuxiAg2FRFHLCdBebeLEHo/aDXMEK0M9YPDW4wdTT6Ammtt8IvFhegcgmX0v4xBT GT7HfV//WX4/x/yyc4ojBsHm5KiysPiI/G02s0q0xY0d5haRV7UmSqRPR/xtCc8zwsz3aA lWwcDXRvf+PsfoyJ46jNqa6exaYw61s= Date: Thu, 3 Oct 2024 10:53:16 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v6 0/8] drm: zynqmp_dp: IRQ cleanups and debugfs support To: Tomi Valkeinen Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, David Airlie , Michal Simek , Daniel Vetter , "Sagar, Vishal" , Laurent Pinchart , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Dmitry Baryshkov , dri-devel@lists.freedesktop.org References: <20240809193600.3360015-1-sean.anderson@linux.dev> <5e9769dd-459a-4ff3-aebb-bb7057192733@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 10/2/24 10:50, Tomi Valkeinen wrote: > Hi, > > On 01/10/2024 21:31, Sean Anderson wrote: >> On 8/9/24 15:35, Sean Anderson wrote: >>> This series cleans up the zyqnmp_dp IRQ and locking situation. Once >>> that's done, it adds debugfs support. The intent is to enable compliance >>> testing or to help debug signal-integrity issues. > > I think the patches 1-7 look fine, and I think I can pick those already to drm-misc if you're ok with that. > > I'm a bit unsure about patch 8, probably mainly because I don't have experience with the compliance testing. > > How have you tested this? With some DP analyzer/tester, I presume? For my test setup I used an oscilloscope hooked up to the displayport output using a fixture that broke the signals out to SMA. Since the oscilloscope cannot emulate a sink, I first had the output connected to a monitor. Then I disabled HPD and reconnected the output to my fixture. This process is described in more detail in the documentation. > I think none of this (patch 8) is needed by almost anybody. Well, I found it very useful for debugging a signal integrity issue I was having. Once I could have a look at the signals it was very clear what the problem was. > Even among zynqmp_dp developers I assume it's very rare to have the > hardware for this. I wonder if it would make sense to have the debugfs > and related code behind a compile option (which would be nice as the > code wouldn't even compiled in), or maybe a module parameter (which > would be nice as then "anyone" can easily enable it for compliance > testing). What do you think? Other drivers with these features just enabled it unconditionally, so I didn't bother with any special config. > I also somehow recall that there was some discussion earlier about > how/if other drivers support compliance testing. But I can't find the > discussion. Do you remember if there was such discussion, and what was > the conclusion? With a quick look, everything in the debugfs looks > generic, not xilinx specific. The last it got discussed was back in [1], but I never got any further response. I agree that some of this is generic, and could probably be reworked into some internal helpers. But I don't have the bandwidth at the moment to do that work. --Sean [1] http://lore.kernel.org/dri-devel/cda22b0c-8d7c-4ce2-9a7c-3b5ab540fa1f@linux.dev