On 18/10/18 1:21 PM, Anisse Astier wrote:
> If we don't have the voltage switch DSM methods available, there's no
> point in advertising to the rest of the kernel that we support 1.8V, or
> support voltage switch at all.
>
> This fixes an issue on a Gemini Lake (GLK) laptop : eMMC driver will
> timeout on boot (from 60seconds to 10minutes ) as the cqhci attempts CQE
> recovery after a failed voltage switch. In earlier kernels, the problem
> existed, but only delayed boot for about 10 seconds after an I/O error,
> allowing booting on the eMMC (almost) unnoticed.
Can you send the kernel messages? Which kernel is it? Which laptop? An
acpidump might help too.
>
> Signed-off-by: Anisse Astier <anisse@xxxxxxxxx>
> ---
> Hi,
>
> I'm looking forward to your feedback on this patch. Is it safe to
> have no voltage switch method ? Should the quirk be used or skipped
> entirely ?
The eMMC is typically 1.8V only and the voltage switch does nothing. I have
been meaning to tidy it up, but it seemed like it was working so it didn't
get much priority, until now.
>
> It seemed to work well in my tests, as the mmc core works properly.
>
> Regards,
>
> Anisse
>
> drivers/mmc/host/sdhci-pci-core.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index 7bfd366d970d..8fac8cbc5ce8 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -706,10 +706,27 @@ static int intel_execute_tuning(struct mmc_host *mmc, u32 opcode)
> static void byt_probe_slot(struct sdhci_pci_slot *slot)
> {
> struct mmc_host_ops *ops = &slot->host->mmc_host_ops;
> + struct intel_host *intel_host = sdhci_pci_priv(slot);
>
> byt_read_dsm(slot);
>
> ops->execute_tuning = intel_execute_tuning;
> +
> + /* Check if we have the appropriate voltage switch DSM methods */
> + if (!(intel_host->dsm_fns & (1 << INTEL_DSM_V18_SWITCH))) {
> + pr_info("%s: no DSM function for 1.8 voltage switch\n",
> + mmc_hostname(slot->host->mmc));
> + slot->host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> +
> + if (!(intel_host->dsm_fns & (1 << INTEL_DSM_V33_SWITCH))) {
> + /* No voltage switching supported at all, there's no
> + * point in installing the callback: return.
> + */
> + pr_info("%s: Voltage switching unsupported\n",
> + mmc_hostname(slot->host->mmc));
> + return;
> + }
> + }
> ops->start_signal_voltage_switch = intel_start_signal_voltage_switch;
> }
>
>
