Messages in this thread | | | Date | Fri, 23 Aug 2013 19:44:03 +0200 | From | Sebastian Hesselbarth <> | Subject | Re: [RFC 17/17] clk: zynq: remove call to of_clk_init |
| |
On 08/23/13 19:19, Sören Brinkmann wrote: > On Fri, Aug 23, 2013 at 11:30:18AM +0200, Sebastian Hesselbarth wrote: >> On 08/23/13 02:59, Sören Brinkmann wrote: >>> On Thu, Aug 22, 2013 at 05:26:47PM -0700, Sören Brinkmann wrote: >>>> On Tue, Aug 20, 2013 at 04:04:31AM +0200, Sebastian Hesselbarth wrote: >>>>> With arch/arm calling of_clk_init(NULL) from time_init(), we can now >>>>> remove it from corresponding drivers/clk code. >>>> >>>> I think that would break Zynq. >>>> If I see this correctly you call of_clk_init() from common code, >>>> _before_ the SOC specific time init function is called. >>>> The problem is, that we have code setting up a global pointer which is >>>> required by zynq_clk_setup() which is triggered when of_clk_init() is >>>> called. > [ ... ] >> thanks for looking into this. I also had a look at the files in >> question. Based on Steffen's proposal, I prepared a diff that should do >> the trick. It moves zynq_slcr_init() to early_init, instead of reusing >> another hook that has magic cow powers (it calls irqchip_init that zynq >> also wants sooner or later). >> >> Also, it removes zynq_clock_init() and let zynq_clk_setup() map the >> register itself by finding the node and use of_iomap(). I realized that >> clock registers are quite separated within slcr, so you can consider >> to have your own node for the clk-provider. As Steffen is proposing >> this but mentioned incompatible DT changes, I chose that intermediate >> step above. >> >> It would be great, if you test the diff and prepare a patch out of >> it, that I pick-up in the patch set. That way, we also have your >> Signed-off on it. > > I looked into this. Looks like init_early() happens to early. I suspect > slab is missing to make zynq_slcr_init() work. So, I moved it into > init_irq(). Is there any init_call() type which is called at the correct > time?
Sören,
I mistakenly assumed init_early is after mm, so of course my proposal does not work as it should. I am fine with moving it to init_irq() until you find the best solution (or until we have the same "mess" with default init_irq hook).
> I looked briefly into syscon and regmap, and that does actually look > promising and to really fix this mess, I guess we have to wait a little > until Steffen finishes his work on it.
IIRC, both syscon and regmap will require you to have devices ready. I haven't followed all recent discussions about early device registration. Anyway, it will not help much in the current approach to get rid of custom .init_timer and maybe .init_irq later.
> To facilitate Sebastian's series I came up with the patch below. > The problem I have is, I do not really want the clkc to map the > registers. They are in the SLCR and the SLCR driver is doing it, hence > we should work with what that driver provides - which ideally would be > based on regmap and syscon, but we're not there yet. Hence I somehow > need to pass the SLCR pointer to the clkc. To avoid accessing the global > pointer directly I kept the zynq_clock_init() routine which is called > from zynq_slcr_init().
For this patch set I'd be fine with the proposal below. For the short run, you could consider to hide register accesses to slcr by providing zynq_slcr_readl/writel instead of passing just the base address.
But again, that will require either custom .init_time or .init_irq to set up slcr before clocks.
> That is the best I could come up with quickly and w/o investing a lot of > time to figure out the regmap and syscon stuff, which seems to be handled > by Steffen already, anyway. > It is essentially a stripped down version of Sebastian's proposal.
If there are no general objections, I take that one for the real patch set.
Sebastian
-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |