From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Date: Tue, 25 Sep 2018 09:45:12 -0500 References: <1536955389-30442-1-git-send-email-pdeschrijver@nvidia.com> <1536955389-30442-15-git-send-email-pdeschrijver@nvidia.com> <5baa1ae9.1c69fb81.1ab9.1805@mx.google.com> <20180925130329.GK7636@tbergstrom-lnx.Nvidia.com> In-Reply-To: <20180925130329.GK7636@tbergstrom-lnx.Nvidia.com> Message-ID: Subject: Re: [RFC 14/14] dt-bindings: tegra: Add Tegra210 EMC binding From: Rob Herring Content-Type: text/plain; charset="UTF-8" To: Peter De Schrijver Cc: vkuruturi@nvidia.com, linux-clk , linux-tegra@vger.kernel.org, Thierry Reding , Jon Hunter , devicetree@vger.kernel.org, daniel@octaforge.org, Andre Heider , swtcr0@gmail.com List-ID: On Tue, Sep 25, 2018 at 8:03 AM Peter De Schrijver wrote: > > On Mon, Sep 24, 2018 at 02:04:24PM -0700, Rob Herring wrote: > > On Fri, Sep 14, 2018 at 11:03:09PM +0300, Peter De Schrijver wrote: > > > Signed-off-by: Peter De Schrijver > > > > Needs a commit msg. > > > > > --- > > > .../memory-controllers/nvidia,tegra210-emc.txt | 448 +++++++++++++++++++++ > > > 1 file changed, 448 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/memory-controllers/nvidia,tegra210-emc.txt > > > > > > diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra210-emc.txt b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra210-emc.txt > > > new file mode 100644 > > > index 0000000..1c52f47 > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra210-emc.txt > > > @@ -0,0 +1,448 @@ > > > +NVIDIA Tegra210 SoC EMC (external memory controller) > > > +==================================================== > > > + > > > +Required properties : > > > +- compatible : Should be "nvidia,tegra21-emc", "nvidia,tegra124-emc". > > > +- reg : physical base address and length of the controller's registers. > > > +- nvidia,memory-controller : phandle of the MC driver. > > > > Huh? What is this block then? > > > > > +- clocks : phandles of the possible source clocks > > > +- clock-names : names of the possible source clocks > > > + > > > +The node should contain a "emc-table" subnode for each supported RAM type > > > +(see field RAM_CODE in register PMC_STRAPPING_OPT_A), with its unit address > > > +being its RAM_CODE. > > > > Unit address is based on reg property. > > > > > + > > > +Required properties for "emc-table" nodes : > > > +- nvidia,ram-code : Should contain the value of RAM_CODE this timing set is > > > +used for. > > > + > > > +Each "emc-table" node should contain a "emc-table" subnode for every supported > > > +EMC clock rate. The "emc-table" subnodes should have the clock rate in kHz as > > > +their unit address. > > > + > > > +Required properties for "emc-table" nodes : > > > > Which emc-table nodes, the child or grand-child nodes? > > > > > +- compatible "nvidia,tegra21-emc-table", "nvidia,tegra210-emc-table" > > > > > +- nvidia,revision : revision of the parameter set used for this node. All > > > + nodes in the same "emc-table" should have the same revision > > > +- clock-frequency : frequency in kHz > > > +- nvidia,emc-min-mv : minimum voltage for this OPP > > > +- nvidia,gk20a-min-mv : minimum GPU voltage for this OPP > > > +- nvidia,source : clock source to be used for this OPP > > > > Is this memory timings/settings or OPPs? We have a binding for OPPs > > already. > > > > > +- nvidia,src-sel-reg : value of EMC CAR register to be used for this OPP > > > +- nvidia,needs-training : 1 if the OPP needs training at boot, 0 otherwise > > > +- nvidia,trained : 1 if initial training has been done by firmware, 0 otherwise > > > +- nvidia,periodic_training : 1 if the OPP needs periodic training, 0 otherwise > > > +- nvidia,trained_dram_clktree_c0d0u0 : training data word > > > +- nvidia,trained_dram_clktree_c0d0u1 : training data word > > > > [...] > > > > This is a huge list of properties. For all the things that are memory > > timings, is there really value to defining a property for each setting? > > Perhaps you should just define your own format and either make it a > > separate firmware file or include that file in the dtb. > > > > The problem with moving to a binary blob is that it will break compatibility > with existing devices (eg. Jetson TX1 and shield TV) because their bootloaders > rely on the existing format. Good to know, but not really my problem that bindings shipped without review. While this is self-contained and doesn't have any sort of common binding which could be used instead, can you say that about *everything* the bootloader depends on. Rob