Re: [PATCH] mmc: sdhci-pci-gli: GL9767: Wait for UHS-II PHY before LPM

[Matthew Schwartz <matthew.schwartz@linux.dev>]

On 11/4/26 3:13 AM, Adrian Hunter wrote:
> On 22/10/2026 02:33, Matthew Schwartz wrote:
>> sdhci_gl9767_set_clock() re-enables low power negotiation right after
>> releasing the UHS-II PHY reset. If the bus then goes idle before the
>> PHY has settled, every SDHCI MMIO read returns all-ones for about 250
>> us. sdhci_uhs2_interface_detect() takes that as IF_DETECT and LANE_SYNC
>> set, so a UHS-I only microSD card is treated as UHS-II. The attach then
>> either fails with "SDHCI_UHS2_CAPS_PTR(65535) is wrong" or, if the
>> registers come back before the CAPS_PTR read, runs DEVICE_INIT 30 times
>> with a 10 second timeout each and delays card detection by 5 minutes.
>>
>> Config register 0x8CC reads 0x2000 from clock enable until about 250-300
>> us after the PHY reset release and 0x1000 otherwise. Poll its bit 13
>> before re-enabling low power negotiation. The register meaning is
>> inferred from that behaviour, and with the wait in place 12 of 12
>> UHS-II probes of a UHS-I card correctly found no UHS-II interface.
>>
>> Fixes: 27dd3b82557a ("mmc: sdhci-pci-gli: enable UHS-II mode for GL9767")
>> Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
> 
> One comment below, otherwise:
> 
> Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> 
>> ---
>>  drivers/mmc/host/sdhci-pci-gli.c | 29 ++++++++++++++++++++++++++++-
>>  1 file changed, 28 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
>> index b55618566d651..bd383918d27c7 100644
>> --- a/drivers/mmc/host/sdhci-pci-gli.c
>> +++ b/drivers/mmc/host/sdhci-pci-gli.c
>> @@ -205,6 +205,9 @@
>>  #define   PCIE_GLI_9767_COMBO_MUX_CTL_RST_EN		  BIT(6)
>>  #define   PCIE_GLI_9767_COMBO_MUX_CTL_WAIT_PERST_EN	  BIT(10)
>>  
>> +#define PCIE_GLI_9767_PHY_STS			0x8CC
>> +#define   PCIE_GLI_9767_PHY_STS_UHS2_BUSY	  BIT(13)
>> +
>>  #define PCIE_GLI_9767_PWR_MACRO_CTL					0x8D0
>>  #define   PCIE_GLI_9767_PWR_MACRO_CTL_LOW_VOLTAGE			  GENMASK(3, 0)
>>  #define   PCIE_GLI_9767_PWR_MACRO_CTL_LD0_LOW_OUTPUT_VOLTAGE		  GENMASK(15, 12)
>> @@ -1190,6 +1193,27 @@ static void gl9767_set_low_power_negotiation(struct pci_dev *pdev, bool enable)
>>  	gl9767_vhs_read(pdev);
>>  }
>>  
>> +static u32 gl9767_read_phy_sts(struct pci_dev *pdev)
>> +{
>> +	u32 value;
>> +
>> +	pci_read_config_dword(pdev, PCIE_GLI_9767_PHY_STS, &value);
>> +
>> +	return value;
>> +}
>> +
>> +static void sdhci_gl9767_uhs2_wait_phy_ready(struct sdhci_host *host)
>> +{
>> +	struct sdhci_pci_slot *slot = sdhci_priv(host);
>> +	struct pci_dev *pdev = slot->chip->pdev;
>> +	u32 value;
>> +
>> +	if (read_poll_timeout_atomic(gl9767_read_phy_sts, value,
>> +				     !(value & PCIE_GLI_9767_PHY_STS_UHS2_BUSY),
>> +				     10, 10000, false, pdev))
> 
> Doesn't look like this needs to be atomic

Makes sense, will fix in v2.

> 
>> +		pr_warn("%s: UHS-II PHY not ready after reset.\n", mmc_hostname(host->mmc));
>> +}
>> +
>>  static void sdhci_gl9767_uhs2_phy_reset(struct sdhci_host *host, bool assert)
>>  {
>>  	struct sdhci_pci_slot *slot = sdhci_priv(host);
>> @@ -1276,9 +1300,12 @@ static void sdhci_gl9767_set_clock(struct sdhci_host *host, unsigned int clock)
>>  
>>  	sdhci_enable_clk(host, clk);
>>  
>> -	if (mmc_card_uhs2(host->mmc))
>> +	if (mmc_card_uhs2(host->mmc)) {
>>  		/* De-assert reset */
>>  		sdhci_gl9767_uhs2_phy_reset(host, false);
>> +		/* Low power negotiation before the PHY settles makes MMIO read all-ones */
>> +		sdhci_gl9767_uhs2_wait_phy_ready(host);
>> +	}
>>  
>>  	gl9767_set_low_power_negotiation(pdev, true);
>>  }
>