| Message ID | 20230221190858.3159617-5-evan@rivosinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | RISC-V Hardware Probing User Interface | expand |
Hey Evan, On Tue, Feb 21, 2023 at 11:08:55AM -0800, Evan Green wrote: > From: Palmer Dabbelt <palmer@rivosinc.com> > > This key allows device trees to specify the performance of misaligned > accesses to main memory regions from each CPU in the system. Could you fold some of Palmer's explanation for why this must be in the devicetree? Think this is where he explained it: https://lore.kernel.org/all/mhng-8736b349-e27a-4372-81ca-3a25d2ec1e94@palmer-ri-x1c9/ > > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> > Signed-off-by: Evan Green <evan@rivosinc.com> > --- > > Changes in v3: > - Added | to description: to make dt-checker happy. > > Documentation/devicetree/bindings/riscv/cpus.yaml | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml > index c6720764e765..f79e9e5c5ee9 100644 > --- a/Documentation/devicetree/bindings/riscv/cpus.yaml > +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml > @@ -85,6 +85,21 @@ properties: > $ref: "/schemas/types.yaml#/definitions/string" > pattern: ^rv(?:64|32)imaf?d?q?c?b?v?k?h?(?:_[hsxz](?:[a-z])+)*$ > > + riscv,misaligned-access-performance: > + description: | > + Identifies the performance of misaligned memory accesses to main memory > + regions. There are three flavors of unaligned access performance: "emulated" > + means that misaligned accesses are emulated via software and thus > + extremely slow, "slow" means that misaligned accesses are supported by > + hardware but still slower that aligned accesses sequences, and "fast" s/that/than/ > + means that misaligned accesses are as fast or faster than the > + cooresponding aligned accesses sequences. s/cooresponding/corresponding/ Thanks, Conor. > + $ref: "/schemas/types.yaml#/definitions/string" > + enum: > + - emulated > + - slow > + - fast > + > # RISC-V requires 'timebase-frequency' in /cpus, so disallow it here > timebase-frequency: false > > -- > 2.25.1 >
On Mon, Feb 27, 2023 at 10:57:55PM +0000, Conor Dooley wrote: > Hey Evan, > > On Tue, Feb 21, 2023 at 11:08:55AM -0800, Evan Green wrote: > > From: Palmer Dabbelt <palmer@rivosinc.com> > > > > This key allows device trees to specify the performance of misaligned > > accesses to main memory regions from each CPU in the system. > > Could you fold some of Palmer's explanation for why this must be in the > devicetree? Think this is where he explained it: > https://lore.kernel.org/all/mhng-8736b349-e27a-4372-81ca-3a25d2ec1e94@palmer-ri-x1c9/ I still don't think this belongs in DT and replied on the above thread. Rob
diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml index c6720764e765..f79e9e5c5ee9 100644 --- a/Documentation/devicetree/bindings/riscv/cpus.yaml +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml @@ -85,6 +85,21 @@ properties: $ref: "/schemas/types.yaml#/definitions/string" pattern: ^rv(?:64|32)imaf?d?q?c?b?v?k?h?(?:_[hsxz](?:[a-z])+)*$ + riscv,misaligned-access-performance: + description: | + Identifies the performance of misaligned memory accesses to main memory + regions. There are three flavors of unaligned access performance: "emulated" + means that misaligned accesses are emulated via software and thus + extremely slow, "slow" means that misaligned accesses are supported by + hardware but still slower that aligned accesses sequences, and "fast" + means that misaligned accesses are as fast or faster than the + cooresponding aligned accesses sequences. + $ref: "/schemas/types.yaml#/definitions/string" + enum: + - emulated + - slow + - fast + # RISC-V requires 'timebase-frequency' in /cpus, so disallow it here timebase-frequency: false