Re: [PATCH 05/11] OMAPDSS: add clk_prepare and clk_unprepare
On Monday 25 June 2012 06:44 PM, Tomi Valkeinen wrote:
venc and hdmi use clk_enable/disable in runtime PM callbacks (suspend& resume). If I understand correctly, the callbacks are not called in atomic context if pm_runtime_irq_safe() has not been used. And it is not used in omapdss. dsi uses clk_enable/disable in a different manner, but not in atomic context. So as far as I see, clocks are never handled in atomic context. Is everything related to the base clk stuff already in mainline? Can I take the clk_prepare/unprepare patch into my omapdss tree?
Well the Common Clk framework is already in mainline, but we still don;t have CONFIG_COMMON_CLK enabled for our builds yet. So until we do so, clk_prepare/unprepare will just be stubs which do nothing. I will repost the patch getting rid of the clk_prepare/unprepare and adding clk_prepare_enable/disable_unprepare instead.
A question about clk_prepare/unprepare, not directly related: let's say I have a driver for some HW block. The driver doesn't use clk functions, but uses runtime PM. The driver also sets pm_runtime_irq_safe(). Now, the driver can call pm_runtime_get_sync() in an atomic context, and this would lead to the underlying framework (hwmod, omap_device, I don't know who =) enabling the func clock for that HW. But this would happen in atomic context, so the underlying framework can't use clk_prepare. How does the underlying framework handle that case? (sorry if that's a stupid question =).
No, its not a stupid question at all. I have been thinking about this too to figure out whats the best way to handle this. For now, the patches I posted, do an early clk_prepare (like I did for dss) for all hwmod clocks as I have no way to know which ones will have their _enable, _idle etc called in atomic context. Maybe I should see if there is a way I can do so only for those devices which end up calling a pm_runtime_irq_safe() and not do it early for all.
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