[PATCH v2 02/10] pwm: Allow chips to support multiple PWMs.
From: Thierry Reding <hidden>
Date: 2012-02-08 10:31:20
Also in:
linux-devicetree, linux-tegra
* Russell King - ARM Linux wrote:
On Wed, Feb 08, 2012 at 09:15:08AM +0100, Thierry Reding wrote:quoted
* Ryan Mallon wrote:quoted
On 07/02/12 02:19, Thierry Reding wrote:quoted
The total maximum number of PWM devices is currently fixed to 64, but can easily be made configurable via Kconfig.It would be better to make the code handle arbitrary numbers of PWMs. A Kconfig knob becomes annoying when you have more than one platform configured into the kernel.AFAICT handling an arbitrary number of PWMs will only be possible once we get rid of the global namespace and therefore should be postponed for later. I may be wrong, though, so if anybody can point me in the right direction I'm perfectly happy to change that in this series.One solution would be to look at how genirq handles this. Eg, it uses a radix tree to store the irqdescs rather than an array, and a bitmap showing which global numbers are allocated.
That's exactly the solution implemented by this second version of the series. In fact I did turn to genirq for inspiration at the time I wrote the code. My understanding was that Ryan proposed to get rid of the bitmap altogether because it arbitrarily limits the number of PWMs. How that can be achieved with a global namespace I don't know. Thus my proposal to keep it as-is for now and get rid of it once per-chip indexing is implemented. Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 198 bytes Desc: not available URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20120208/c61c04bf/attachment-0001.sig>