On 6/10/21 5:05 AM, Luca Ceresoli wrote: > Hi Sean, > > On 07/06/21 17:49, Sean Anderson wrote: >> This property allows setting the SD/OE pin's polarity to active-high, >> instead of the default of active-low. >> >> Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx> > > Thanks. > >> + idt,sd-active-high: >> + $ref: /schemas/types.yaml#/definitions/flag >> + description: SD/OE pin polarity is active-high > > I think the name "sd" is misleading. I do as well. After sending this patch, I reviewed the documentation again and discovered that the functionality was not as clear as I initially thought. > In the Renesas docs (which are very confusing on their own about this > topic) this bit is called "SP" -- *S*D/OE *P*olarity. But actually it > controls polarity of the SD/OE pin only if the pin is configured for > "OE" function: > >> SP bit = “SD/OE pin Polarity Bit”: Set the polarity of the SD/OE >> pin where outputs enable or disable. Only works with OE, not with SD. > (VC6E register and programming guide [0]) > > As such I suggest you use either "sp" to keep the naming used in the > Renesas docs or "oe" as it actually controls OE polarity only. I do > prefer "sp" as it helps matching with the datasheets, but maybe adding a > little more detail in bindings docs to clarify, as in: > > idt,sp-active-high: > $ref: /schemas/types.yaml#/definitions/flag > description: SD/OE pin polarity is active-high > (only works when SD/OE pin is configured as OE) > > BTW is it only me finding the "Shutdown Function" of [0] completely > confusing? Also, Table 24 has contradictory lines and missing lines. I'm > sending a request to Renesas support to ask them to clarify it all. I rearranged the table to highlight which bits cause the output to become inactive: SH SP OSn OEn SD/OE OUT x x 1 0 x Active 0 0 1 1 0 Active 0 0 1 1 1 Inactive 0 1 1 1 0 Inactive 0 1 1 1 1 Active 1 0 1 1 0 Active 1 0 x x 1 Shutdown 1 1 1 1 0 Inactive 1 1 x x 1 Shutdown x x 0 x x Inactive This may be condensed to SH SP SD/OE function for 0/1 0 0 Active/Inactive 0 1 Inactive/Active 1 0 Active/Shutdown 1 1 Inactive/Shutdown According to the datasheet, the default settings are SH=0 and SP=0. So perhaps a good set of properties would be idt,enable-shutdown: Shutdown the device when the SD/OE pin is high. This would set SH=1. idt,output-enable-active-high: Disable output when the SD/OE pin is low. This would set SP=1. --Sean > > [0] > https://www.renesas.com/eu/en/document/mau/versaclock-6e-family-register-descriptions-and-programming-guide >
