From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Wed, 11 Mar 2020 06:27:37 -0600 Subject: [PATCH v1 1/2] clk: socfpga: Read the clock parent's register base in probe function In-Reply-To: References: <1583742120-6661-1-git-send-email-chee.hong.ang@intel.com> <1583742120-6661-2-git-send-email-chee.hong.ang@intel.com> 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 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. Regards, Simon