lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 13 Feb 2018 09:38:38 -0800 From: Channa <ckadabi@...eaurora.org> To: Mark Rutland <mark.rutland@....com> Cc: linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org, linux-arm@...ts.infradead.org, linux-kernel@...r.kernel.org, tsoni@...eaurora.org, sboyd@...eaurora.org, kyan@...eaurora.org Subject: Re: [PATCH 1/2] dt-bindings: Documentation for qcom,llcc On 2018-02-13 06:37, Mark Rutland wrote: > On Tue, Feb 06, 2018 at 11:56:50AM -0800, Channa wrote: >> On 2018-02-02 03:05, Mark Rutland wrote: >> > On Thu, Feb 01, 2018 at 12:39:09PM -0800, Channa wrote: >> > > On 2018-02-01 02:44, Mark Rutland wrote: >> > > > On Thu, Jan 25, 2018 at 03:55:12PM -0800, Channagoud Kadabi wrote: >> > > > > +- llcc-bank-off: >> > > > > + Usage: required >> > > > > + Value Type: <u32 array> >> > > > > + Definition: Offsets of llcc banks from llcc base address starting >> > > > > from >> > > > > + LLCC bank0. >> > > > > + >> > > > > +- llcc-broadcast-off: >> > > > > + Usage: required >> > > > > + Value Type: <u32> >> > > > > + Definition: Offset of broadcast register from LLCC bank0 address. >> > > > >> > > > Please could we use "offset" rather than "off" for both of these? That >> > > > way it's obvious these aren't properties for disabling some feature. >> > > > >> > > > How variable are these offsets in practice? Is the memory map not fixed? >> > > >> > > The offsets depends on the number of LLCC HW blocks. These number of >> > > HW >> > > blocks vary from >> > > chipset to chipset and new registers could be added that changes the >> > > offset. >> > >> > Surely if new registers are added, we need a new compatible string? >> > >> > Can't we encode the number of LLCC HW blocks, instead? Presumably that >> > would give enough information to cover both llcc-bank-off and >> > llcc-broadcast-off. >> > >> > [...] >> >> Are you suggesting to move these offset handing out of DTS files and >> manage >> in the driver? > > Something like that, though it depends on how exactly the offsets can > be > derived. > > Using reg entries, as Matt suggested, sounds better though. > >> > > > > +compatible devices: >> > > > > + qcom,sdm845-llcc >> > > > >> > > > Huh? The "qcom,sdm845-llcc" bindings wasn't described above, and it's >> > > > not clear what this means. >> > > > >> > > > > + >> > > > > +Example: >> > > > > + >> > > > > + qcom,system-cache@...0000 { >> > > > > + compatible = "qcom,llcc-core", "syscon", "simple-mfd"; >> > > > >> > > > This looks very wrong. Why do you need syscon and simple-mfd? >> > > >> > > LLCC HW block has 3 functionalities: >> > > System cache core, ECC & AMON drivers for debugging. >> > > All three drivers use the same register space for configuration, >> > > status etc. >> > > In order to avoid remapping the same address region across multiple >> > > drivers, >> > > I have implemented this driver as a syncon and simple-mfd. >> > >> > Please don't do that; that's completely dependent on Linux >> > implementation details. >> >> Why do you think simple-mfd is not good here? The LLCC HW clock is >> outside >> of CPUSS and has >> multiple functional blocks. > > For one thing, there's no need for this to be a syscon *and* a > simple-mfd. > > W.R.T. simple-mfd, I think it would bet better to decompose the device > in a top-level driver, as I described in my prior reply, rather than > describing a set of drivers (which are not themselves HW). > >> > > > > +- cache-slices: >> > > > > + Usage: required >> > > > > + Value type: <prop-encoded-array> >> > > > > + Definition: The tuple has phandle to llcc device as the first >> > > > > argument and the >> > > > > + second argument is the usecase id of the client. >> > > > >> > > > What is a "usecase id" ? >> > > >> > > Usecase id for use case that wants to use system cache for eg: >> > > video-encode >> > > and video-decode >> > >> > Sure, but how is the value used? Is it the index of a slice? Or >> > something more abstract? >> >> This is used as an index to the SCT (System cache Table) configuration >> data that controls the behavior of each cache slice. > > Ok. Where does that SCT live? Is that in HW? Is it programmed by SW, or > statically configured for a given platform? SCT is in the HW. Kernel driver programs these settings for a given platform. The table is also used to lookup size, cache slice id details requested by client drivers. > > Thanks, > Mark. -- -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
Powered by blists - more mailing lists