Hi Krzysztof, On 13 October 2015 at 05:44, Krzysztof Kozlowski <k.kozlow...@samsung.com> wrote: > On 13.10.2015 00:32, Anand Moon wrote: >> Hi Krzysztof, >> >> On 12 October 2015 at 11:14, Krzysztof Kozlowski >> <k.kozlow...@samsung.com> wrote: >>> On 12.10.2015 00:46, Anand Moon wrote: >>>> Added support for UHS-I bus speed 50MB/s (SDR50, DDR50) 104MB/s (SDR104) >>> >>> This description is not entirely correct. The MMC driver already >>> supports these UHS speeds (you did not any code) so you rather enabled >>> it (description of bindings says "is supported"). >>> >>> You mentioned DDR50 but I don't see respective property below. >>> >>> How do you know that these modes are really supported? I don't know. Can >>> you convince me? >> >> Setting this DDR50 capability give me this error. That's the reason to >> drop this capability. > > But you mentioned it in commit message! "Added support for UHS-I ... > (DDR50)" > > In the same time dropping DDR50 is not an sufficient proof that "SDR50 > and SDR104 are really supported". >
These changes are related to the microSD card capabilities. So SDR50 have better frequency over DDR50. On the same Sandisk card. When the card select the capability for DDR50 --------------------------------------------------- [ 4.001477] mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0) [ 4.001604] mmc1: new ultra high speed DDR50 SDHC card at address aaaa [ 4.004505] mmcblk0: mmc1:aaaa SL32G 29.7 GiB [ 4.009179] mmcblk0: error -110 sending status command, retrying [ 4.009271] mmcblk0: error -115 sending stop command, original cmd response 0x900, card status 0x900 [ 4.009275] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0x0 [ 4.025563] mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 400000Hz, actual 396825HZ div = 63) [ 4.067770] Console: switching to colour frame buffer device 274x77 [ 4.098782] mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0) [ 4.099692] mmc1: tried to reset card [ 4.101332] mmcblk0: p1 p2 When the card select the capability for SDR50 --------------------------------------------------------------------------------- [ 2.439806] mmc_host mmc1: Bus speed (slot 0) = 100000000Hz (slot req 100000000Hz, actual 100000000HZ div = 0) [ 2.449729] mmc1: new ultra high speed SDR50 SDHC card at address aaaa [ 2.455984] mmcblk0: mmc1:aaaa SL32G 29.7 GiB [ 2.461743] mmcblk0: p1 p2 Which will relate to better read/write speed. -Anand Moon > Best regards, > Krzysztof > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
