Re: [PATCH V2 04/10] mmc: sdhci-iproc: Cap min clock frequency on BCM2711
From: Ulf Hansson <hidden>
Date: 2021-08-16 14:00:32
Also in:
linux-arm-kernel, linux-mmc
On Sat, 7 Aug 2021 at 13:07, Stefan Wahren [off-list ref] wrote:
From: Nicolas Saenz Julienne <nsaenz@kernel.org> There is a known bug on BCM2711's SDHCI core integration where the controller will hang when the difference between the core clock and the bus clock is too great. Specifically this can be reproduced under the following conditions: - No SD card plugged in, polling thread is running, probing cards at 100 kHz. - BCM2711's core clock configured at 500MHz or more. So set 200 kHz as the minimum clock frequency available for that board. For more information on the issue see this: https://lore.kernel.org/linux-mmc/20210322185816.27582-1-nsaenz@kernel.org/T/#m11f2783a09b581da6b8a15f302625b43a6ecdeca (local) Fixes: f84e411c85be ("mmc: sdhci-iproc: Add support for emmc2 of the BCM2711") Signed-off-by: Nicolas Saenz Julienne <nsaenz@kernel.org> Signed-off-by: Stefan Wahren <redacted>
Applied for fixes and by adding a stable tag, thanks! Kind regards Uffe
quoted hunk ↗ jump to hunk
--- drivers/mmc/host/sdhci-iproc.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)diff --git a/drivers/mmc/host/sdhci-iproc.c b/drivers/mmc/host/sdhci-iproc.c index cce390f..032bf85 100644 --- a/drivers/mmc/host/sdhci-iproc.c +++ b/drivers/mmc/host/sdhci-iproc.c@@ -173,6 +173,23 @@ static unsigned int sdhci_iproc_get_max_clock(struct sdhci_host *host) return pltfm_host->clock; } +/* + * There is a known bug on BCM2711's SDHCI core integration where the + * controller will hang when the difference between the core clock and the bus + * clock is too great. Specifically this can be reproduced under the following + * conditions: + * + * - No SD card plugged in, polling thread is running, probing cards at + * 100 kHz. + * - BCM2711's core clock configured at 500MHz or more + * + * So we set 200kHz as the minimum clock frequency available for that SoC. + */ +static unsigned int sdhci_iproc_bcm2711_get_min_clock(struct sdhci_host *host) +{ + return 200000; +} + static const struct sdhci_ops sdhci_iproc_ops = { .set_clock = sdhci_set_clock, .get_max_clock = sdhci_iproc_get_max_clock,@@ -271,6 +288,7 @@ static const struct sdhci_ops sdhci_iproc_bcm2711_ops = { .set_clock = sdhci_set_clock, .set_power = sdhci_set_power_and_bus_voltage, .get_max_clock = sdhci_iproc_get_max_clock, + .get_min_clock = sdhci_iproc_bcm2711_get_min_clock, .set_bus_width = sdhci_set_bus_width, .reset = sdhci_reset, .set_uhs_signaling = sdhci_set_uhs_signaling, --2.7.4