On 8/9/22 09:57, Krzysztof Kozlowski wrote: > On 09/08/2022 10:52, Patrice CHOTARD wrote: >> Hi Krzystof >> >> On 8/9/22 07:29, Krzysztof Kozlowski wrote: >>> On 09/08/2022 07:18, Krzysztof Kozlowski wrote: >>>> On 08/08/2022 19:08, Patrice CHOTARD wrote: >>>>> Hi Krzystof >>>>> >>>>> On 8/8/22 11:01, Krzysztof Kozlowski wrote: >>>>>> On 08/08/2022 10:40, patrice.chotard@xxxxxxxxxxx wrote: >>>>>>> From: Patrice Chotard <patrice.chotard@xxxxxxxxxxx> >>>>>>> >>>>>>> Add new property st,dual-flash which allows to use the QSPI interface as a >>>>>>> communication channel using up to 8 qspi line. >>>>>>> This mode can only be used if cs-gpios property is defined. >>>>>>> >>>>>>> Signed-off-by: Patrice Chotard <patrice.chotard@xxxxxxxxxxx> >>>>>>> --- >>>>>>> Documentation/devicetree/bindings/spi/st,stm32-qspi.yaml | 8 ++++++++ >>>>>>> 1 file changed, 8 insertions(+) >>>>>>> >>>>>>> diff --git a/Documentation/devicetree/bindings/spi/st,stm32-qspi.yaml b/Documentation/devicetree/bindings/spi/st,stm32-qspi.yaml >>>>>>> index 6ec6f556182f..5e4f9109799e 100644 >>>>>>> --- a/Documentation/devicetree/bindings/spi/st,stm32-qspi.yaml >>>>>>> +++ b/Documentation/devicetree/bindings/spi/st,stm32-qspi.yaml >>>>>>> @@ -46,6 +46,14 @@ properties: >>>>>>> - const: tx >>>>>>> - const: rx >>>>>>> >>>>>>> + st,dual-flash: >>>>>>> + type: boolean >>>>>>> + description: >>>>>>> + Allows to use 8 data lines in case cs-gpios property is defined. >>>>>> >>>>>> It's named dual-flash, but what if you want to use QSPI to connect for >>>>>> example to FPGA? >>>>>> >>>>>> Also how is this related to parallel-memories property? >>>>> >>>>> I called it "dual-flash" simply because it enable the dual flash feature of the QSPI block (bit CR_DFM : Dual Flash Mode) >>>>> which allows to use the 8 lines simultaneously of our dual QSPI block. >>>> >>>> And how is it related to existing parallel-memories property? >>> >>> Maybe I was not specific enough, so let me rephrase - we have already >>> parallel-memories property. How this one is different (to justify the >>> new property)? Is just one memory connected in your case to QSPI over 8 >>> data lines? >> >> Our QSPI block is a dual Quad-SPI memory interface, it can managed 2 QSPI flashes independently. >> There is a specific mode, dual flash mode, where the 2 QSPI flashes can be accessed simultaneously >> using 8 data lines. In this case, both throughput and capacity are two fold with this mode. >> >> To illustrate, you can have a look at STM32MP157 reference manual (chapter 27.3.1 figure 172) available here: >> https://www.st.com/resource/en/reference_manual/rm0436-stm32mp157-advanced-armbased-32bit-mpus-stmicroelectronics.pdf >> >> As you mentioned above, the goal is to connect a FPGA to this 8 lines bus. >> >> Hope it clarifies enough ;-) > > Only partially. Based on the explanation above, it looks like you want > to use existing parallel-memories property. Please use that one, instead > of adding a new property for the same feature. Okay, got it, i didn't notice the parallel-memories property recently added. Thanks for pointing it. Patrice > > Best regards, > Krzysztof
