From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ang, Chee Hong Date: Thu, 2 Apr 2020 02:44:14 +0000 Subject: [PATCH v1 1/2] clk: socfpga: Read the clock parent's register base in probe function In-Reply-To: <7fa85609-d547-1784-d00a-2812cb6d8ea4@denx.de> References: <1583742120-6661-1-git-send-email-chee.hong.ang@intel.com> <1583742120-6661-2-git-send-email-chee.hong.ang@intel.com> <7fa85609-d547-1784-d00a-2812cb6d8ea4@denx.de> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de > On 4/2/20 4:34 AM, Simon Glass wrote: > > Hi, > > > > On Tue, 31 Mar 2020 at 20:33, Ang, Chee Hong > wrote: > >> > >>> Hi Marek, > >>> > >>> On Wed, 11 Mar 2020 at 05:55, Marek Vasut wrote: > >>>> > >>>> On 3/11/20 12:50 PM, Simon Glass wrote: > >>>>> Hi, > >>>> > >>>> Hi, > >>>> > >>>>> On Mon, 9 Mar 2020 at 02:22, wrote: > >>>>>> > >>>>>> From: Chee Hong Ang > >>>>>> > >>>>>> This commit (82de42fa14682d408da935adfb0f935354c5008f) calls > >>>>>> child's > >>>>>> ofdata_to_platdata() method before the parent is probed in dm core. > >>>>>> This has caused the driver no longer able to get the correct > >>>>>> parent clock's register base in the ofdata_to_platdata() method > >>>>>> because the parent clocks will only be probed after the child's > ofdata_to_platdata(). > >>>>>> To resolve this, the clock parent's register base will only be > >>>>>> retrieved by the child in probe() method instead of ofdata_to_platdata(). > >>>>> > >>>>> I think one thing that is going on here is that DM allows ofdata > >>>>> to be read for a device before its parent devices have been read, > >>>>> but it requires that parent devices be probed before their children. > >>>> > >>>> This seems wrong. The clock driver should be able to instantiate > >>>> devices and read their ofdata without probing them. That is one of > >>>> the core design principles of the DM. > >>> > >>> That's a different question. Yes you can read ofdata without probing a > device. > >>> That's why we have two methods. > >>> > >>> The point I am making is that at present there is no requirement > >>> that a parent's ofdata be read before a child's ofdata is read. But > >>> there is a requirement that a parent be probed before a child is probed. > >>> > >>>> > >>>>> The idea is that it should be possible to read the ofdata for a > >>>>> node without needing to have done so for parents. But perhaps this > >>>>> assumption is too brave? > >>>> > >>>> Why is it brave ? That's how it always was, the DT is already > >>>> there, so why wouldn't you be able to read it. > >>> > >>> That was my thinking too. But we are finding in a few situations > >>> that the child's ofdata depends on the parent's. For example, the > >>> parent may have a base address, or a range mapping, or something > >>> else that is needed for the child to correctly get its base address, etc. > >>> > >>>> > >>>>> I suspect we could change this, so that > >>>>> device_ofdata_to_platdata() first calls itself on its parent. > >>>>> > >>>>> I can think of various reasons why this change might be desirable. > >>>> > >>>> I think this is how it worked before already. > >>> > >>> Well effectively, yes, because ofdata and probe were joined together. > > > >> Simon, do you have plan to fix this DM core issue ? > > > > I'm not sure it definitely should be changed. But I'll do a patch and > > see how it looks. > > Do I understand it correctly that the patch > 82de42fa14682d408da935adfb0f935354c5008f actually completely breaks > SoCFPGA ? Then I would say this is a release blocker ? Yes. A10 SPL won't boot at all. It crashes during the clock manager setup.