From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Swapnil Jakhade <sjakhade@cadence.com>, <airlied@linux.ie>,
<daniel@ffwll.ch>, <Laurent.pinchart@ideasonboard.com>,
<robh+dt@kernel.org>, <a.hajda@samsung.com>,
<narmstrong@baylibre.com>, <jonas@kwiboo.se>,
<jernej.skrabec@siol.net>, <dri-devel@lists.freedesktop.org>,
<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <mparab@cadence.com>, <yamonkar@cadence.com>, <jsarha@ti.com>,
<nsekhar@ti.com>, <praneeth@ti.com>, <nikhil.nd@ti.com>
Subject: Re: [PATCH v9 2/3] drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge
Date: Tue, 1 Sep 2020 11:34:45 +0300 [thread overview]
Message-ID: <e53e87b0-7e0a-763f-8b8b-0dc278e1f225@ti.com> (raw)
In-Reply-To: <1598862215-10222-3-git-send-email-sjakhade@cadence.com>
Hi Swapnil,
On 31/08/2020 11:23, Swapnil Jakhade wrote:
> + line_thresh1 = ((vs + 1) << 5) * 8 / bpp;
> + line_thresh2 = (pxlclock << 5) / 1000 / rate * (vs + 1) - (1 << 5);
> + line_thresh = line_thresh1 - line_thresh2 / mhdp->link.num_lanes;
> + line_thresh = (line_thresh >> 5) + 2;
These calculations do not seem to go correctly. There's no comment what's the logic here, but e.g.
for 640x480 (pxlclock 31500) with 1.62Gbps link, I get vs=4, and then the second line above comes to:
(31500 << 5) / 1000 / 162 * (4+1) - (1<<5) = -0.8888888888888893
The result is line_thresh of 100663299.
Tomi
--
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next prev parent reply other threads:[~2020-09-01 8:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-31 8:23 [PATCH v9 0/3] drm: Add support for Cadence MHDP8546 DPI/DP bridge and J721E wrapper Swapnil Jakhade
2020-08-31 8:23 ` [PATCH v9 1/3] dt-bindings: drm/bridge: Document Cadence MHDP8546 bridge bindings Swapnil Jakhade
2020-08-31 8:23 ` [PATCH v9 2/3] drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge Swapnil Jakhade
2020-08-31 20:17 ` Laurent Pinchart
2020-09-01 7:46 ` Tomi Valkeinen
2020-09-01 8:03 ` Tomi Valkeinen
2020-09-04 2:29 ` Laurent Pinchart
2020-09-04 5:53 ` Tomi Valkeinen
2020-09-01 8:34 ` Tomi Valkeinen [this message]
2020-09-03 6:22 ` Milind Parab
2020-09-03 7:23 ` Tomi Valkeinen
2020-09-03 7:32 ` Milind Parab
2020-08-31 8:23 ` [PATCH v9 3/3] drm: bridge: cdns-mhdp8546: Add TI J721E wrapper Swapnil Jakhade
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