linux-kernel - Re: [PATCH] pci/quirks: Add quirk for Bayhub O2 SD controller

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Date:   Thu, 9 Dec 2021 11:05:56 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Rajat Jain <rajatja@...gle.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        rajatxjain@...il.com, jsbarnes@...gle.com, gwendal@...gle.com
Subject: Re: [PATCH] pci/quirks: Add quirk for Bayhub O2 SD controller

On Wed, 8 Dec 2021 at 01:09, Rajat Jain <rajatja@...gle.com> wrote:
>
> This particular SD controller from O2 / Bayhub only allows dword
> accesses to its LTR max latency registers:
> https://github.com/rajatxjain/public_shared/blob/main/OZ711LV2_appnote.pdf
>
> Thus add a quirk that saves and restores these registers
> manually using dword acesses:
> LTR Max Snoop Latency Register
> LTR Max No-Snoop Latency Register
>
> Signed-off-by: Rajat Jain <rajatja@...gle.com>

Acked-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe


> ---
>  drivers/mmc/host/sdhci-pci.h |  1 -
>  drivers/pci/quirks.c         | 39 ++++++++++++++++++++++++++++++++++++
>  include/linux/pci_ids.h      |  1 +
>  3 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci.h b/drivers/mmc/host/sdhci-pci.h
> index 5e3193278ff9..d47cc0ba7ca4 100644
> --- a/drivers/mmc/host/sdhci-pci.h
> +++ b/drivers/mmc/host/sdhci-pci.h
> @@ -10,7 +10,6 @@
>  #define PCI_DEVICE_ID_O2_SDS1          0x8421
>  #define PCI_DEVICE_ID_O2_FUJIN2                0x8520
>  #define PCI_DEVICE_ID_O2_SEABIRD0      0x8620
> -#define PCI_DEVICE_ID_O2_SEABIRD1      0x8621
>
>  #define PCI_DEVICE_ID_INTEL_PCH_SDIO0  0x8809
>  #define PCI_DEVICE_ID_INTEL_PCH_SDIO1  0x880a
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 003950c738d2..b7bd19802744 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5857,3 +5857,42 @@ static void nvidia_ion_ahci_fixup(struct pci_dev *pdev)
>         pdev->dev_flags |= PCI_DEV_FLAGS_HAS_MSI_MASKING;
>  }
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NVIDIA, 0x0ab8, nvidia_ion_ahci_fixup);
> +
> +/*
> + * Bayhub OZ711LV2 SD controller has an errata that only allows DWORD accesses
> + * to the LTR max latency registers. Thus need to save and restore these
> + * registers manually.
> + */
> +static void o2_seabird1_save_ltr(struct pci_dev *dev)
> +{
> +       struct pci_cap_saved_state *save_state;
> +       u32 *reg32;
> +
> +       save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
> +       if (save_state) {
> +               reg32 = &save_state->cap.data[0];
> +               /* Preserve PCI_LTR_MAX_SNOOP_LAT & PCI_LTR_MAX_NOSNOOP_LAT */
> +               pci_read_config_dword(dev, 0x234, reg32);
> +       } else {
> +               pci_err(dev, "quirk can't save LTR snoop latency\n");
> +       }
> +}
> +
> +static void o2_seabird1_restore_ltr(struct pci_dev *dev)
> +{
> +       struct pci_cap_saved_state *save_state;
> +       u32 *reg32;
> +
> +       save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_LTR);
> +       if (save_state) {
> +               reg32 = &save_state->cap.data[0];
> +               /* Restore PCI_LTR_MAX_SNOOP_LAT & PCI_LTR_MAX_NOSNOOP_LAT */
> +               pci_write_config_dword(dev, 0x234, *reg32);
> +       } else {
> +               pci_err(dev, "quirk can't restore LTR snoop latency\n");
> +       }
> +}
> +DECLARE_PCI_FIXUP_SUSPEND_LATE(PCI_VENDOR_ID_O2, PCI_DEVICE_ID_O2_SEABIRD1,
> +                              o2_seabird1_save_ltr);
> +DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_O2, PCI_DEVICE_ID_O2_SEABIRD1,
> +                              o2_seabird1_restore_ltr);
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index 011f2f1ea5bb..6ed16aa38196 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -1717,6 +1717,7 @@
>  #define PCI_DEVICE_ID_O2_8221          0x8221
>  #define PCI_DEVICE_ID_O2_8320          0x8320
>  #define PCI_DEVICE_ID_O2_8321          0x8321
> +#define PCI_DEVICE_ID_O2_SEABIRD1      0x8621
>
>  #define PCI_VENDOR_ID_3DFX             0x121a
>  #define PCI_DEVICE_ID_3DFX_VOODOO      0x0001
> --
> 2.34.1.400.ga245620fadb-goog
>