On Wed, 2024-03-20 at 15:28 +0300, Maxim Kiselev wrote: > Hi Xi, Drew > > I have the same problem with SD on my LicheePi 4A. > > After some investigations I found how to fix this tuning error. > Here is the patch that increases tuning loop count from > 40(MAX_TUNING_LOOP at sdhci.c) to 128. > > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c > b/drivers/mmc/host/sdhci-of-dwcmshc.c > index 8d6cfb648096..da8f5820fb69 100644 > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c > @@ -706,6 +706,7 @@ static int th1520_execute_tuning(struct sdhci_host > *host, u32 opcode) > > /* perform tuning */ > sdhci_start_tuning(host); > + host->tuning_loop_count = 128: > host->tuning_err = __sdhci_execute_tuning(host, opcode); > if (host->tuning_err) { > /* disable auto-tuning upon tuning error */ > > After that change tuning works fine. The same value of loop count is > used in RevyOS BSP > https://github.com/revyos/thead-kernel/blob/c6d4e5df18a17903d012ffd89e67d0ee5ce6cf2d/drivers/mmc/host/sdhci-of-dwcmshc.c#L185 > > Honestly, it looks a little bit strange for me. > > It seems that the tuning algorithm requires to move through > all the taps of delay line(128 taps?) even if we use THRESHOLD_MODE > instend LARGEST_WIN_MODE (I mean bit 2 in AT_CTRL_R(0x540) register). > > Xi, could you also test my fix on your board? I'll try it this weekend. Now having some work with "real time priority" to do :(. -- Xi Ruoyao <xry111@xxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University