On Fri, Jan 31, 2020 at 05:46:39PM +0200, Andy Shevchenko wrote: > On Fri, Jan 31, 2020 at 2:03 PM John Garry <john.garry@xxxxxxxxxx> wrote: > > On 31/01/2020 11:39, Andy Shevchenko wrote: > > > DataBitLength is the size, in bits, of the smallest transfer unit for > > > this connection. _LEN is automatically > > > created to refer to this portion of the resource descriptor. > > > Is it what you are looking for? (As far as I know most of the > > > firmwares simple abuse this field among others) > > I didn't think so - I thought that there was a distinction between width > > and length in SPI terms. > My interpretation of this field is a data width of the slave. > Basically what we have as transfer->size inside SPI in the Linux > kernel. This discussion is about the number of data lines, SPI_TX_QUAD and friends. > 1 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x08, > 36 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x10, > 35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x18, > 35 SpiSerialBusV2(0x0000,PolarityLow,FourWireMode,0x20, > 1 SpiSerialBusV2(0x0000,PolarityLow,ThreeWireMode,0x10, > 8 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x08, > 1 SpiSerialBusV2(0x0001,PolarityLow,FourWireMode,0x10, > So, it seems I stand corrected, the field is in right use, although > cases like 0x10 and 0x20 should be carefully checked. Those look like they're mainly controlling SPI_3WIRE so it does look like a reasonable fit, yes.
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