On Mon, Mar 07, 2016 at 05:05:45PM -0800, Matt Roper wrote:
> From: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
>
> This is needed for WM computation workaround for arbitrated display
> bandwidth.
>
> v2: Address Matt's review comments
> - Be more paranoid while dmi decoding
> - Also add support for decoding speed from configured memory speed
> if availble in DMI memory entry
>
> v3 (by Matt):
> - Use memdev_dmi_entry from dmi.h
> - Don't try to use/compare negative numbers in unsigned types
>
> Cc: matthew.d.roper@xxxxxxxxx
> Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
> Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_dma.c | 34 ++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/i915_drv.h | 7 +++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 4aa3db6..4259afe 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -49,6 +49,7 @@
> #include <linux/pm.h>
> #include <linux/pm_runtime.h>
> #include <linux/oom.h>
> +#include <linux/dmi.h>
>
>
> static int i915_getparam(struct drm_device *dev, void *data,
> @@ -973,6 +974,33 @@ static void i915_mmio_cleanup(struct drm_device *dev)
> pci_iounmap(dev->pdev, dev_priv->regs);
> }
>
> +static void dmi_decode_memory_info(const struct dmi_header *hdr, void *priv)
> +{
> + struct drm_i915_private *dev_priv = (struct drm_i915_private *) priv;
> + const struct memdev_dmi_entry *memdev =
> + (const struct memdev_dmi_entry *)hdr;
> + uint16_t mem_speed = 0;
> +
> + if (hdr->type != DMI_ENTRY_MEM_DEVICE)
> + return;
> +
> + /* Get the speed */
> + if (hdr->length > offsetof(struct memdev_dmi_entry, conf_mem_clk_speed))
> + mem_speed = memdev->conf_mem_clk_speed;
> + else if (hdr->length > offsetof(struct memdev_dmi_entry, speed))
> + mem_speed = memdev->speed;
> + else
> + return;
> +
> + dev_priv->dmi.mem_channel++;
> +
> + /* All channels are expected to have same the speed */
> + if (dev_priv->dmi.mem_speed == 0)
> + dev_priv->dmi.mem_speed = mem_speed;
> + else if (mem_speed != dev_priv->dmi.mem_speed)
> + dev_priv->dmi.valid = false;
> +}
Dunno if this was covered already, but trusting DMI for this feels
rather fragile to me. Isn't there some way to get the relevant
information from the hardware itself?
> +
> /**
> * i915_driver_load - setup chip and create an initial config
> * @dev: DRM device
> @@ -1000,6 +1028,12 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
> dev->dev_private = dev_priv;
> dev_priv->dev = dev;
>
> + /* walk the dmi device table for getting platform memory information */
> + dev_priv->dmi.valid = true;
> + dmi_walk(dmi_decode_memory_info, dev_priv);
> + if (!dev_priv->dmi.mem_speed)
> + dev_priv->dmi.valid = false;
> +
> /* Setup the write-once "constant" device info */
> device_info = (struct intel_device_info *)&dev_priv->info;
> memcpy(device_info, info, sizeof(dev_priv->info));
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index f37ac12..a2a7d8d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2022,6 +2022,13 @@ struct drm_i915_private {
> * NOTE: This is the dri1/ums dungeon, don't add stuff here. Your patch
> * will be rejected. Instead look for a better place.
> */
> +
> + /* DMI data for memory bandwidth calculation */
> + struct {
> + bool valid;
> + uint16_t mem_channel;
> + int16_t mem_speed;
> + } dmi;
> };
>
> static inline struct drm_i915_private *to_i915(const struct drm_device *dev)
> --
> 2.1.4
>
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--
Ville Syrjälä
Intel OTC
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