Re: [PATCH] drm/i915/csr: Allow matching unknown HW steppings with generic firmware

Imre Deak
2016-03-07T13:12:43Z

On ma, 2016-03-07 at 12:05 +0000, Chris Wilson wrote:
> If the firmware is generic and has a run-anywhere mode, enable it rather
> than completely failing on unknown HW revisions.
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Damien Lespiau <damien.lespiau@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Sunil Kamath <sunil.kamath@intel.com>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Animesh Manna <animesh.manna@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>

Looks ok:
Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
> This is probably stable@ material since it could allow future hw to
> just work.

Existing platforms will select the generic firmware version already if
one is provided in the image, this change will just allow us not to
provide a stepping info table for new platforms. So not sure why it's
@stable material.

--Imre

> -Chris
> ---
>  drivers/gpu/drm/i915/intel_csr.c | 46 +++++++++++++++++-----------------------
>  1 file changed, 19 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
> index 902054efb902..575a5821d2a1 100644
> --- a/drivers/gpu/drm/i915/intel_csr.c
> +++ b/drivers/gpu/drm/i915/intel_csr.c
> @@ -188,28 +188,31 @@ static const struct stepping_info bxt_stepping_info[] = {
>   {'B', '0'}, {'B', '1'}, {'B', '2'}
>  };
>
> -static const struct stepping_info *intel_get_stepping_info(struct drm_device *dev)
> +static const struct stepping_info no_stepping_info = { '*', '*' };
> +
> +static const struct stepping_info *
> +intel_get_stepping_info(struct drm_i915_private *dev_priv)
>  {
>   const struct stepping_info *si;
>   unsigned int size;
>
> - if (IS_KABYLAKE(dev)) {
> + if (IS_KABYLAKE(dev_priv)) {
>   size = ARRAY_SIZE(kbl_stepping_info);
>   si = kbl_stepping_info;
> - } else if (IS_SKYLAKE(dev)) {
> + } else if (IS_SKYLAKE(dev_priv)) {
>   size = ARRAY_SIZE(skl_stepping_info);
>   si = skl_stepping_info;
> - } else if (IS_BROXTON(dev)) {
> + } else if (IS_BROXTON(dev_priv)) {
>   size = ARRAY_SIZE(bxt_stepping_info);
>   si = bxt_stepping_info;
>   } else {
> - return NULL;
> + size = 0;
>   }
>
> - if (INTEL_REVID(dev) < size)
> - return si + INTEL_REVID(dev);
> + if (INTEL_REVID(dev_priv) < size)
> + return si + INTEL_REVID(dev_priv);
>
> - return NULL;
> + return &no_stepping_info;
>  }
>
>  /**
> @@ -252,13 +255,11 @@ bool intel_csr_load_program(struct drm_i915_private *dev_priv)
>  static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>         const struct firmware *fw)
>  {
> - struct drm_device *dev = dev_priv->dev;
>   struct intel_css_header *css_header;
>   struct intel_package_header *package_header;
>   struct intel_dmc_header *dmc_header;
>   struct intel_csr *csr = &dev_priv->csr;
> - const struct stepping_info *stepping_info = intel_get_stepping_info(dev);
> - char stepping, substepping;
> + const struct stepping_info *si = intel_get_stepping_info(dev_priv);
>   uint32_t dmc_offset = CSR_DEFAULT_FW_OFFSET, readcount = 0, nbytes;
>   uint32_t i;
>   uint32_t *dmc_payload;
> @@ -266,14 +267,6 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>   if (!fw)
>   return NULL;
>
> - if (!stepping_info) {
> - DRM_ERROR("Unknown stepping info, firmware loading failed\n");
> - return NULL;
> - }
> -
> - stepping = stepping_info->stepping;
> - substepping = stepping_info->substepping;
> -
>   /* Extract CSS Header information*/
>   css_header = (struct intel_css_header *)fw->data;
>   if (sizeof(struct intel_css_header) !=
> @@ -285,7 +278,7 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>
>   csr->version = css_header->version;
>
> - if ((IS_SKYLAKE(dev) || IS_KABYLAKE(dev)) &&
> + if ((IS_SKYLAKE(dev_priv) || IS_KABYLAKE(dev_priv)) &&
>       csr->version < SKL_CSR_VERSION_REQUIRED) {
>   DRM_INFO("Refusing to load old Skylake DMC firmware v%u.%u,"
>    " please upgrade to v%u.%u or later"
> @@ -313,11 +306,11 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>   /* Search for dmc_offset to find firware binary. */
>   for (i = 0; i < package_header->num_entries; i++) {
>   if (package_header->fw_info[i].substepping == '*' &&
> -     stepping == package_header->fw_info[i].stepping) {
> +     si->stepping == package_header->fw_info[i].stepping) {
>   dmc_offset = package_header->fw_info[i].offset;
>   break;
> - } else if (stepping == package_header->fw_info[i].stepping &&
> - substepping == package_header->fw_info[i].substepping) {
> + } else if (si->stepping == package_header->fw_info[i].stepping &&
> +    si->substepping == package_header->fw_info[i].substepping) {
>   dmc_offset = package_header->fw_info[i].offset;
>   break;
>   } else if (package_header->fw_info[i].stepping == '*' &&
> @@ -325,7 +318,8 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>   dmc_offset = package_header->fw_info[i].offset;
>   }
>   if (dmc_offset == CSR_DEFAULT_FW_OFFSET) {
> - DRM_ERROR("Firmware not supported for %c stepping\n", stepping);
> + DRM_ERROR("Firmware not supported for %c stepping\n",
> +   si->stepping);
>   return NULL;
>   }
>   readcount += dmc_offset;
> @@ -371,9 +365,7 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>   return NULL;
>   }
>
> - memcpy(dmc_payload, &fw->data[readcount], nbytes);
> -
> - return dmc_payload;
> + return memcpy(dmc_payload, &fw->data[readcount], nbytes);
>  }
>
>  static void csr_load_work_fn(struct work_struct *work)