Hi Adrian, On Wednesday 20 December 2017 07:41 PM, Adrian Hunter wrote: > On 14/12/17 15:09, Kishon Vijay Abraham I wrote: >> Errata i834 in AM572x Sitara Processors Silicon Revision 2.0, 1.1 >> (SPRZ429K July 2014–Revised March 2017 [1]) mentions >> Under high speed HS200 and SDR104 modes, the functional clock for MMC >> modules will reach up to 192 MHz. At this frequency, the maximum obtainable >> timeout (DTO = 0xE) through MMC host controller is (1/192MHz)*2^27 = 700ms. >> Commands taking longer than 700ms may be affected by this small window >> frame. Workaround for this errata is use a software timer instead of >> hardware timer to provide the delay requested by the upper layer. >> >> While this errata is specific to AM572x, it is applicable to all sdhci >> based controllers when a particular request require timeout greater >> than hardware capability. > > It doesn't work for our controllers. Even if the data timeout interrupt is > disabled, it seems like the timeout still "happens" in some fashion - after > which the host controller starts misbehaving. even if the data timeout doesn't get disabled, count = 0xE is still present. So ideally this shouldn't break any existing platforms no? > > So you will need to add a quirk. > >> >> Re-use the software timer already implemented in sdhci to program the >> correct timeout value and also disable the hardware timeout when >> the required timeout is greater than hardware capabiltiy in order to >> avoid spurious timeout interrupts. >> >> This patch is based on the earlier patch implemented for omap_hsmmc [2] >> >> [1] -> http://www.ti.com/lit/er/sprz429k/sprz429k.pdf >> [2] -> https://patchwork.kernel.org/patch/9791449/ >> >> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> >> --- >> drivers/mmc/host/sdhci.c | 41 +++++++++++++++++++++++++++++++++++++++-- >> drivers/mmc/host/sdhci.h | 11 +++++++++++ >> 2 files changed, 50 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >> index e9290a3439d5..d0655e1d2cc7 100644 >> --- a/drivers/mmc/host/sdhci.c >> +++ b/drivers/mmc/host/sdhci.c >> @@ -673,6 +673,27 @@ static void sdhci_adma_table_post(struct sdhci_host *host, >> } >> } >> >> +static void sdhci_calc_sw_timeout(struct sdhci_host *host, >> + struct mmc_command *cmd, >> + unsigned int target_timeout) >> +{ >> + struct mmc_host *mmc = host->mmc; >> + struct mmc_ios *ios = &mmc->ios; >> + struct mmc_data *data = cmd->data; >> + unsigned long long transfer_time; >> + >> + if (data) { >> + transfer_time = MMC_BLOCK_TRANSFER_TIME_MS(data->blksz, >> + ios->bus_width, >> + ios->clock); > > If it has a value, actual_clock is better than ios->clock. okay. > >> + /* calculate timeout for the entire data */ >> + host->data_timeout = (data->blocks * (target_timeout + >> + transfer_time)); >> + } else if (cmd->flags & MMC_RSP_BUSY) { >> + host->data_timeout = cmd->busy_timeout * MSEC_PER_SEC; > > Doesn't need MSEC_PER_SEC multiplier. right. > >> + } >> +} >> + >> static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd) >> { >> u8 count; >> @@ -732,8 +753,12 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd) >> } >> >> if (count >= 0xF) { >> - DBG("Too large timeout 0x%x requested for CMD%d!\n", >> - count, cmd->opcode); >> + DBG("Too large timeout.. using SW timeout for CMD%d!\n", >> + cmd->opcode); >> + sdhci_calc_sw_timeout(host, cmd, target_timeout); >> + host->ier &= ~SDHCI_INT_DATA_TIMEOUT; >> + sdhci_writel(host, host->ier, SDHCI_INT_ENABLE); >> + sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE); >> count = 0xE; >> } >> >> @@ -1198,6 +1223,14 @@ static void sdhci_finish_command(struct sdhci_host *host) >> { >> struct mmc_command *cmd = host->cmd; >> >> + if (host->data_timeout) { >> + unsigned long timeout; >> + >> + timeout = jiffies + >> + msecs_to_jiffies(host->data_timeout); >> + sdhci_mod_timer(host, host->cmd->mrq, timeout); > > cmd could be the sbc or a stop cmd or a command during transfer, so this > needs more logic. host->data_timeout gets set only for data commands or commands with busy timeout. But I guess for commands during data transfer, host->data_timeout might still be set? Checking sdhci_data_line_cmd(mrq->cmd) in addition to host->data_timeout should take care of all cases right? > >> + } >> + >> host->cmd = NULL; >> >> if (cmd->flags & MMC_RSP_PRESENT) { >> @@ -2341,6 +2374,10 @@ static bool sdhci_request_done(struct sdhci_host *host) >> return true; >> } >> >> + host->data_timeout = 0; >> + host->ier |= SDHCI_INT_DATA_TIMEOUT; >> + sdhci_writel(host, host->ier, SDHCI_INT_ENABLE); >> + sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE); > > sdhci can have 2 requests in progress to allow for commands to be sent while > a data transfer is in progress, so this is not necessarily the data transfer > request that is done. Also we want to avoid unnecessary register writes. > okay.. got it. >> sdhci_del_timer(host, mrq); >> >> /* >> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h >> index 54bc444c317f..e6e0278bea1a 100644 >> --- a/drivers/mmc/host/sdhci.h >> +++ b/drivers/mmc/host/sdhci.h >> @@ -332,6 +332,15 @@ struct sdhci_adma2_64_desc { >> /* Allow for a a command request and a data request at the same time */ >> #define SDHCI_MAX_MRQS 2 >> >> +/* >> + * Time taken for transferring one block. It is multiplied by a constant >> + * factor '2' to account for any errors >> + */ >> +#define MMC_BLOCK_TRANSFER_TIME_MS(blksz, bus_width, freq) \ >> + ((unsigned long long) \ >> + (2 * (((blksz) * MSEC_PER_SEC * \ >> + (8 / (bus_width))) / (freq)))) > > I don't think the macro helps make the code more readable. Might just as > well write a nice function to calculate the entire data request timeout. okay. > >> + >> enum sdhci_cookie { >> COOKIE_UNMAPPED, >> COOKIE_PRE_MAPPED, /* mapped by sdhci_pre_req() */ >> @@ -546,6 +555,8 @@ struct sdhci_host { >> /* Host SDMA buffer boundary. */ >> u32 sdma_boundary; >> >> + unsigned long long data_timeout; > > msecs_to_jiffies() will truncate to 'unsigned int' anyway, so this might as > well be 'unsigned int'. > okay. Thanks Kishon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
