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    SubjectRe: Major 2.6.38 / 2.6.39 / 3.0 regression ignored?
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    On Fri, 22 Jul 2011 15:08:06 +0400, Kirill Smelkov <kirr@mns.spb.ru> wrote:

    > And now after v3.0 is out, I've tested it again, and yes, like it was
    > broken on v3.0-rc5, it is (now even more) broken on v3.0 -- after first
    > bad io access the system freezes completely:

    I looked at this when I first saw it (a couple of weeks ago), and I
    couldn't see any obvious reason this patch would cause this particular
    problem. I didn't want to revert the patch at that point as I feared it
    would cause other subtle problems. Given that you've got a work-around,
    it seemed best to just push this off past 3.0.

    Given the failing address passed to ioread32, this seems like it's
    probably the call to READ_BREADCRUMB -- I915_BREADCRUMB_INDEX is 0x21,
    which is an offset in 32-bit units within the hardware status page. If
    the status_page.page_addr value was zero, then the computed address
    would end up being 0x84.

    And, it looks like status_page.page_addr *will* end up being zero as a
    result of the patch in question. The patch resets the entire ring
    structure contents back to the initial values, which includes smashing
    the status_page structure to zero, clearing the value of
    status_page.page_addr set in i915_init_phys_hws.

    Here's an untested patch which moves the initialization of
    status_page.page_addr into intel_render_ring_init_dri. I note that
    intel_init_render_ring_buffer *already* has the setting of the
    status_page.page_addr value, and so I've removed the setting of
    status_page.page_addr from i915_init_phys_hws.

    I suspect we could remove the memset from intel_init_render_ring_buffer;
    it seems entirely superfluous given the memset in i915_init_phys_hws.

    From 159ba1dd207fc52590ce8a3afd83f40bd2cedf46 Mon Sep 17 00:00:00 2001
    From: Keith Packard <keithp@keithp.com>
    Date: Fri, 22 Jul 2011 10:44:39 -0700
    Subject: [PATCH] drm/i915: Initialize RCS ring status page address in
    intel_render_ring_init_dri

    Physically-addressed hardware status pages are initialized early in
    the driver load process by i915_init_phys_hws. For UMS environments,
    the ring structure is not initialized until the X server starts. At
    that point, the entire ring structure is re-initialized with all new
    values. Any values set in the ring structure (including
    ring->status_page.page_addr) will be lost when the ring is
    re-initialized.

    This patch moves the initialization of the status_page.page_addr value
    to intel_render_ring_init_dri.

    Signed-off-by: Keith Packard <keithp@keithp.com>
    ---
    drivers/gpu/drm/i915/i915_dma.c | 6 ++----
    drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
    2 files changed, 5 insertions(+), 4 deletions(-)

    diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
    index 1271282..8a3942c 100644
    --- a/drivers/gpu/drm/i915/i915_dma.c
    +++ b/drivers/gpu/drm/i915/i915_dma.c
    @@ -61,7 +61,6 @@ static void i915_write_hws_pga(struct drm_device *dev)
    static int i915_init_phys_hws(struct drm_device *dev)
    {
    drm_i915_private_t *dev_priv = dev->dev_private;
    - struct intel_ring_buffer *ring = LP_RING(dev_priv);

    /* Program Hardware Status Page */
    dev_priv->status_page_dmah =
    @@ -71,10 +70,9 @@ static int i915_init_phys_hws(struct drm_device *dev)
    DRM_ERROR("Can not allocate hardware status page\n");
    return -ENOMEM;
    }
    - ring->status_page.page_addr =
    - (void __force __iomem *)dev_priv->status_page_dmah->vaddr;

    - memset_io(ring->status_page.page_addr, 0, PAGE_SIZE);
    + memset_io((void __force __iomem *)dev_priv->status_page_dmah->vaddr,
    + 0, PAGE_SIZE);

    i915_write_hws_pga(dev);

    diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
    index e961568..47b9b27 100644
    --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
    +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
    @@ -1321,6 +1321,9 @@ int intel_render_ring_init_dri(struct drm_device *dev, u64 start, u32 size)
    ring->get_seqno = pc_render_get_seqno;
    }

    + if (!I915_NEED_GFX_HWS(dev))
    + ring->status_page.page_addr = dev_priv->status_page_dmah->vaddr;
    +
    ring->dev = dev;
    INIT_LIST_HEAD(&ring->active_list);
    INIT_LIST_HEAD(&ring->request_list);
    --
    1.7.5.4
    --
    keith.packard@intel.com
    [unhandled content-type:application/pgp-signature]
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