Re: [RFC PATCH 0/2] hw/sd: Deprecate the SPI mode and the SPI to SD adapter
Hi Philippe, On Mon, Jul 6, 2020 at 6:07 AM Philippe Mathieu-Daudé wrote: > > I tried to maintain the SPI mode because it is useful in > tiny embedded devices, and thought it would be helpful for > the AVR MCUs. > As AVR was blocked, I thought it was wise to deprecate the > SPI mode as users are interested in the faster MMC mode. > Today Thomas surprised me by posting an update of it! > https://www.mail-archive.com/qemu-devel@nongnu.org/msg720089.html > > I'm still posting this as RFC to discuss, but I'm reconsiderating > keeping this mode a bit more. > AFAIK, SiFive folks (Pragnesh in cc) are investigating supporting QSPI model on "sifive_u" machine, and it will definitely use this SPI over SD model. In fact, the QSPI is the last big gap in the "sifive_u" machine to make it a complete platform for hardware replacement. Regards, Bin
Re: [RFC PATCH 0/2] hw/sd: Deprecate the SPI mode and the SPI to SD adapter
On 7/10/20 11:27 AM, Bin Meng wrote: > Hi Philippe, > > On Mon, Jul 6, 2020 at 6:07 AM Philippe Mathieu-Daudé wrote: >> >> I tried to maintain the SPI mode because it is useful in >> tiny embedded devices, and thought it would be helpful for >> the AVR MCUs. >> As AVR was blocked, I thought it was wise to deprecate the >> SPI mode as users are interested in the faster MMC mode. >> Today Thomas surprised me by posting an update of it! >> https://www.mail-archive.com/qemu-devel@nongnu.org/msg720089.html >> >> I'm still posting this as RFC to discuss, but I'm reconsiderating >> keeping this mode a bit more. >> > > AFAIK, SiFive folks (Pragnesh in cc) are investigating supporting QSPI > model on "sifive_u" machine, and it will definitely use this SPI over > SD model. > > In fact, the QSPI is the last big gap in the "sifive_u" machine to > make it a complete platform for hardware replacement. Good news! I have some idea about the design, but don't have the time to work on it. Help in this area is welcomed, and I am happy to review the patches. The way I'd do it is keep the generic sd.c code and make it an abstract class (or interface), and split SD / SPI protocols handling in different implementation files. Only the negotiation at reset is common, once you switch to a protocol mode you can't switch to another without resetting the device. Also this would make the MMC protocol (already implemented by Xilinx) upstreamable more easily. Having different files also allows different maintenance granularity. I haven't looked at QSPI, but I expect it to be quite different that the old SPI mode. Regards, Phil.
Re: [RFC PATCH 0/2] hw/sd: Deprecate the SPI mode and the SPI to SD adapter
On Sun, Jul 5, 2020 at 3:08 PM Philippe Mathieu-Daudé wrote: > > I tried to maintain the SPI mode because it is useful in > tiny embedded devices, and thought it would be helpful for > the AVR MCUs. > As AVR was blocked, I thought it was wise to deprecate the > SPI mode as users are interested in the faster MMC mode. > Today Thomas surprised me by posting an update of it! > https://www.mail-archive.com/qemu-devel@nongnu.org/msg720089.html > > I'm still posting this as RFC to discuss, but I'm reconsiderating > keeping this mode a bit more. I think it's worth keeping. I'm pretty sure the HiFive Unleashed (sifive_u in QEMU) uses SD over SPI. There isn't an upstream model but I think there are out of tree patches that hopefully one day will make it upstream. Alistair > > Philippe Mathieu-Daudé (2): > hw/sd/ssi-sd: Deprecate the SPI to SD card 'adapter' > hw/sd/sdcard: Deprecate the SPI mode > > docs/system/deprecated.rst | 10 ++ > 1 file changed, 10 insertions(+) > > -- > 2.21.3 > >
Re: [RFC PATCH 0/2] hw/sd: Deprecate the SPI mode and the SPI to SD adapter
On 7/6/20 6:41 PM, Alistair Francis wrote: > On Sun, Jul 5, 2020 at 3:08 PM Philippe Mathieu-Daudé wrote: >> >> I tried to maintain the SPI mode because it is useful in >> tiny embedded devices, and thought it would be helpful for >> the AVR MCUs. >> As AVR was blocked, I thought it was wise to deprecate the >> SPI mode as users are interested in the faster MMC mode. >> Today Thomas surprised me by posting an update of it! >> https://www.mail-archive.com/qemu-devel@nongnu.org/msg720089.html >> >> I'm still posting this as RFC to discuss, but I'm reconsiderating >> keeping this mode a bit more. > > I think it's worth keeping. > > I'm pretty sure the HiFive Unleashed (sifive_u in QEMU) uses SD over > SPI. There isn't an upstream model but I think there are out of tree > patches that hopefully one day will make it upstream. Glad to hear that! :) > > Alistair > >> >> Philippe Mathieu-Daudé (2): >> hw/sd/ssi-sd: Deprecate the SPI to SD card 'adapter' >> hw/sd/sdcard: Deprecate the SPI mode >> >> docs/system/deprecated.rst | 10 ++ >> 1 file changed, 10 insertions(+) >> >> -- >> 2.21.3 >> >> >
