> > > Hi, Pekon > > > > 2013/8/26 Gupta, Pekon <pekon@xxxxxx>: > > >> > > >> Signed-off-by: wangyuhang <wangyuhang2014@xxxxxxxxx> > > >> --- > > >> Documentation/devicetree/bindings/spi/spi-bus.txt | 14 > > ++++++++++++++ > > >> 1 file changed, 14 insertions(+) > > >> > > >> diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt > > >> b/Documentation/devicetree/bindings/spi/spi-bus.txt > > >> index 296015e..145ba96 100644 > > >> --- a/Documentation/devicetree/bindings/spi/spi-bus.txt > > >> +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt > > >> @@ -55,6 +55,20 @@ contain the following properties. > > >> chip select active high > > >> - spi-3wire - (optional) Empty property indicating device requires > > >> 3-wire mode. > > >> +- spi-tx-nbits - (optional) Number of bits used for MOSI(writting) > > >> +- spi-rx-nbits - (optional) Number of bits used for MISO(reading) > > >> + > > >> +So if for example the slave has 4 wires for writting and 2 wires for > > reading, > > >> +and the spi-tx/rx-nbits property should be set as follows: > > >> + > > >> +spi-tx-nbits = <4>; > > >> +spi-rx-nbits = <2>; > > > [Pekon]: Oh.. Sorry.. I mis-understood your patch here.. So here 'spi-tx-nbits' and 'spi-rx-nbits' specify how many data-channels are actually connected on board to a spi_device.. correct ? And, m25p30 driver will determine what to put in spi_transfer->tx_nbits based on different flash commands .. Correct ? In that sense.. its your approach is correct.. But then please use different binding names, something like below.. s/spi-tx-nbits/spi-tx-max-width s/spi-rx-nbits/spi-rx-max-width ----------------------------------------------- > > > [Pekon]: there is a problem here... > > > spi-tx-nbit = <4> suggests that SPI device support QUAD writes, but it > does > > > not indicate whether DUAL writes are supported by device or not. > > > So, In my view having either of the following implementation could help > > > in specifying capabilities independently and clearly. > > > *Implementation-1 Boolean* > > > spi-tx-quad = <true | false> > > > spi-tx-dual = <true | false> > > > spi-tx-single = <true | false> > > > Same way for Rx.. > > > spi-rx-quad = <true | false> > > > spi-rx-dual = <true | false> > > > spi-rx-single = <true | false> > > > > > > *Implementation-2 Multi-option* > > > spi-quad = <tx-only | rx-only | duplex> > > > spi-dual = <tx-only | rx-only | duplex> > > > spi-single = <tx-only | rx-only | full-duplex | half-duplex> > > > > > Not exactly, spi-tx-nbit = <4> suggests that SPI device will use QUAD > > writes, not support QUAD writes. There is no need to set what mode > > slave supports, user just set the certain mode slave will work in. > > ----------------------------------------------- My above comment is more for DT binding for spi_master (master DT node) probed by controller driver, which can have multiple capabilities. I think you havn't added anything for that .. neither checks for that.. Do you plan to have a patch for that too ? > > >> + > > >> +Now the value that spi-tx-nbits and spi-rx-nbits can receive is only > > >> +1(single), 2(dual) and 4(quad). If you don't set spi-tx-nbits or spi-rx- > nbits, > > >> +spi_device mode will be set in single(1 wire) as default. Another point, > if > > >> +property:spi-3wire is set, spi-tx/rx-nbits is forbidden to set to <2 or 4>, > > >> +otherwise, an errro will return. > > >> > > > [Pekon]: Also, instead of having separate binding for 'spi-3wire', it can be > > > moved under as spi-single = <half-duplex>. > > > Full-duplex = Tx and Rx operate on independent channels and > > concurrently. > > > Half-duplex = Tx and Rx use same bi-directional channel for transmission > > > one by one > > > > > Actually, spi-3wire can be regarded as a part of spi-single, but > > corrected as what you said, there will be some inconvenient. > > 1,the driver that has already used spi-3wire need a big change. > > 2,there have to be a complexed check in spi framework if set like: > > spi-quad = <tx-only | rx-only | duplex> > > spi-dual = <tx-only | rx-only | duplex> > > spi-single = <tx-only | rx-only | full-duplex | half-duplex> > > > [Pekon]: No, I'm not asking you to update logic in all drivers, > just the DT bindings. Something like this.. > @@ -872,46 +872,42 @@ static void of_register_spi_devices(struct > spi_master *master) > /* Device DUAL/QUAD mode */ > prop = of_get_property(nc, "spi-single", &len); > if (prop == HALF_DUPLEX) > spi->mode |= SPI_3WIRE; > > So, you set the same spi->mode[SPI_3WIRE] bit, thus other drivers are not > impacted. And you can deprecate the older "spi-3wire" binding. > > with regards, pekon > > > >> If a gpio chipselect is used for the SPI slave the gpio number will be > > passed > > >> via the cs_gpio > > >> -- > > >> 1.7.9.5 > > > > > > with regards, pekon > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/ ��.n��������+%������w��{.n����z�{��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
