Hi Tomi, On Fri, Oct 11, 2013 at 10:17 AM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > On 11/10/13 10:42, Dr. H. Nikolaus Schaller wrote: > >> I am not sure if there is a SPI driver for a McBSP port [1]? And to make that >> work (reliably) and tested it might need a lot of work for us. At least I think >> such a change (e.g. setting up clock polarity etc.) is not done in some minutes. >> And the only feedback we have from the panel is "does not work"/"works". I.e. >> if we are not lucky that it works immediately we have no real means to debug. >> >> IMHO it also gives more flexibility to board designers to choose GPIOs instead >> of enforcing some SPI interface by the driver (and encapsulate this arguable >> protocol in the driver). Maybe some board has 3 spare GPIOs but neither >> McBSPs nor McSPIs available. > > This has been an interesting thread, I've learnt a lot =). > > I still think the panel driver should not handle this, but there should > be a separate spi bitbang driver for it. > > I understand you're not enthusiastic going that way, as the current > version works for you. However, when using DT, we need to think how to > represent the hardware in the device tree data, and it has to be right > from the beginning. > > That's why I won't allow representing this panel as having 4 gpios in > the DT data, because that is not correct. The panel has 3 pins. But > then, the panel does allow reading, which could be implemented using 4 > gpios as you have done. This data should be in the spi-bitbang data, and > the panel should just use the standard SPI framework. I disagree. There are different drivers which pass in platform data gpios (encoder-tfp410.c or encoder-tpd12s015.c) and those must be covered by DT then. I cannot see problem why to have for td028 panel 3 or 4 gpios defined in DT. > > Using SPI framework does not mean you should use McBSP or McSPI. It's up > to you how the 3-wire SPI is implemented on the SoC side, the panel > would just work in all the cases. > > Tomi > > BR, marek -- as simple and primitive as possible ------------------------------------------------- Marek Belisko - OPEN-NANDRA Freelance Developer Ruska Nova Ves 219 | Presov, 08005 Slovak Republic Tel: +421 915 052 184 skype: marekwhite twitter: #opennandra web: http://open-nandra.com -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
