Re: [RFC 08/17] OMAPDSS: DSI: Maintain own copy of timings in driver data
On Wednesday 08 August 2012 11:45 AM, Tomi Valkeinen wrote:
On Wed, 2012-08-08 at 11:27 +0530, Archit Taneja wrote:I am a bit unclear about resolution when it comes to command mode panels.Right, it's a bit confusing. And I'm not 100% sure how to manage the rotation.For command mode panels, we can perform rotation at the panel side. That is, the panel refreshes itself by fetching pixels from it's buffer in a rotated way. Is that right?Yes. Well, actually I think the panel stores the pixels in rotated manner when it receives them from OMAP, but it's practically the same. One thing to realize is that this kind of rotation is a bit limited: because there's only one buffer, OMAP will write pixels to the buffers at the same time as the panel shows them. When rotating, this leads to tearing. If the panel has double buffer, that solves the problem, but I haven't seen such panels. Another option is to update the panel in two parts, like N9 does, but that's timing sensitive and a bit tricky.If the original resolution is 864x480, and we set rotation at panel side to make the rotation 480x864, the DISPC manager size should also be configured at 480x864 right?Yep. When we use the panel rotation, from OMAP's point of view the panel resolution has changed.We seem to be setting the manager timings only once when DSI is enabled. After that, setting rotation doesn't impact manager size.Hmm, previously the mgr size was set before each update. I wonder if that code has been dropped, probably because we removed the support for partial updates at one point. Without partial updates, the size stays the same, except obviously with rotation. I think I just forgot about rotation at that time.
I tried out rotation on Taal, and it only works for 180 degrees(and 0 of course), 90 and 270 result in no output. I'll add a dss_mgr_set_timings() in omap_dsi_update, that should sort of fix it, but someone would need to reconfigure the connected overlays too before trying out an update.
I am asking this to understand if we need to keep resolution as a separate parameter than timings. That is, timings represents the initial width and height of the panel, and resolution represents the current width and height of the panel.I'm not sure. I think that OMAP doesn't really need to know about the initial resolution. It doesn't really matter from OMAP's point of view. I think I originally kept timings and resolution separately, and the idea was that timings represent the panel's timings, i.e. how it updates the screen from its own memory. And resolution represents the usable resolution, from OMAP's point of view. While I haven't seen such a cmd mode panel, there could be a command sent to the panel to configure its timings. For this we need real timings, not the rotated resolution. However, even in that case the DISPC doesn't need to know about those timings, they would be handled by the panel driver (which could, perhaps, reconfigure the DSI bus speed to match the new timings). So I think that inside omapdss, we don't need separate timings and resolution for DSI cmd mode panels.
Ok. Archit -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html