| Message ID | 20180706162155.8432-2-f4bug@amsat.org |
|---|---|
| State | New |
| Headers | show |
| Series | [for-3.0,1/1] hw/sd/omap_mmc: Split 'pseudo-reset' from 'power-on-reset' | expand |
On 6 July 2018 at 17:21, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: > DeviceClass::reset models a "cold power-on" reset which can > also be use to powercycle a device; but there is no "hot reset" > (a.k.a. soft-reset) method available. > > The OMAP MMC Power-Up Control bit is not designed to powercycle > a card, but to disable it without powering it off (pseudo-reset): > > Multimedia Card (MMC/SD/SDIO) Interface [SPRU765A] > > MMC_CON[11] Power-Up Control (POW) > This bit must be set to 1 before any valid transaction to either > MMC/SD or SPI memory cards. > When 1, the card is considered powered-up and the controller core > is enabled. > When 0, the card is considered powered-down (system dependent), > and the controller core logic is in pseudo-reset state. This is, > the MMC_STAT flags and the FIFO pointers are reset, any access to > MMC_DATA[DATA] has no effect, a write into the MMC.CMD register > is ignored, and a setting of MMC_SPI[STR] to 1 is ignored. This text says that the card "is considered powered-down (system dependent)", so it's not entirely invalid to reset the card here. Still, if the guests get confused by it I guess that the n8x0 systems didn't do that, and certainly resetting the other parts of the controller state is wrong. Strictly I guess we should also check the enable flag for the other things this text calls out: * accesses to MMC_DATA[DATA] * writes to MMC.CMD (we already do this) * setting MMC_SPI[STR] to 1 (we don't emulate MMC_SPI) but we should probably consider that a separate bug. (And the n8x0 boards are pretty much unmaintained currently, so I don't care very much whether we fix it or not. I don't have any working test images -- I have one of uncertain vintage which seems to be flaky when it gets to the mmc card init, but I think it makes a bit more progress with this patch now.) Applied to target-arm.next, thanks. thanks -- PMM
diff --git a/hw/sd/omap_mmc.c b/hw/sd/omap_mmc.c index 671264b650..d0c98ca021 100644 --- a/hw/sd/omap_mmc.c +++ b/hw/sd/omap_mmc.c @@ -1,6 +1,8 @@ /* * OMAP on-chip MMC/SD host emulation. * + * Datasheet: TI Multimedia Card (MMC/SD/SDIO) Interface (SPRU765A) + * * Copyright (C) 2006-2007 Andrzej Zaborowski <balrog@zabor.org> * * This program is free software; you can redistribute it and/or @@ -278,6 +280,12 @@ static void omap_mmc_update(void *opaque) omap_mmc_interrupts_update(s); } +static void omap_mmc_pseudo_reset(struct omap_mmc_s *host) +{ + host->status = 0; + host->fifo_len = 0; +} + void omap_mmc_reset(struct omap_mmc_s *host) { host->last_cmd = 0; @@ -286,11 +294,9 @@ void omap_mmc_reset(struct omap_mmc_s *host) host->dw = 0; host->mode = 0; host->enable = 0; - host->status = 0; host->mask = 0; host->cto = 0; host->dto = 0; - host->fifo_len = 0; host->blen = 0; host->blen_counter = 0; host->nblk = 0; @@ -305,6 +311,8 @@ void omap_mmc_reset(struct omap_mmc_s *host) qemu_set_irq(host->coverswitch, host->cdet_state); host->clkdiv = 0; + omap_mmc_pseudo_reset(host); + /* Since we're still using the legacy SD API the card is not plugged * into any bus, and we must reset it manually. When omap_mmc is * QOMified this must move into the QOM reset function. @@ -459,7 +467,7 @@ static void omap_mmc_write(void *opaque, hwaddr offset, if (s->dw != 0 && s->lines < 4) printf("4-bit SD bus enabled\n"); if (!s->enable) - omap_mmc_reset(s); + omap_mmc_pseudo_reset(s); break; case 0x10: /* MMC_STAT */
DeviceClass::reset models a "cold power-on" reset which can also be use to powercycle a device; but there is no "hot reset" (a.k.a. soft-reset) method available. The OMAP MMC Power-Up Control bit is not designed to powercycle a card, but to disable it without powering it off (pseudo-reset): Multimedia Card (MMC/SD/SDIO) Interface [SPRU765A] MMC_CON[11] Power-Up Control (POW) This bit must be set to 1 before any valid transaction to either MMC/SD or SPI memory cards. When 1, the card is considered powered-up and the controller core is enabled. When 0, the card is considered powered-down (system dependent), and the controller core logic is in pseudo-reset state. This is, the MMC_STAT flags and the FIFO pointers are reset, any access to MMC_DATA[DATA] has no effect, a write into the MMC.CMD register is ignored, and a setting of MMC_SPI[STR] to 1 is ignored. By spliting the 'pseudo-reset' code out of the 'power-on' reset function, this patch fixes a latent bug in omap_mmc_write(MMC_CON)i recently exposed by ecd219f7abb. Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> --- --- hw/sd/omap_mmc.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)