[bug report] drm/xe: Introduce a new DRM driver for Intel GPUs

[Dan Carpenter]

Hello Matthew Brost,

Commit dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel
GPUs") from Mar 30, 2023 (linux-next), leads to the following Smatch
static checker warning:

	drivers/gpu/drm/xe/xe_hw_engine.c:611 read_media_fuses()
	warn: was expecting a 64 bit value instead of '((((1))) << i)'

drivers/gpu/drm/xe/xe_hw_engine.c
    582 static void read_media_fuses(struct xe_gt *gt)
    583 {
    584         struct xe_device *xe = gt_to_xe(gt);
    585         u32 media_fuse;
    586         u16 vdbox_mask;
    587         u16 vebox_mask;
    588         int i, j;
    589 
    590         xe_force_wake_assert_held(gt_to_fw(gt), XE_FW_GT);
    591 
    592         media_fuse = xe_mmio_read32(gt, GT_VEBOX_VDBOX_DISABLE);
    593 
    594         /*
    595          * Pre-Xe_HP platforms had register bits representing absent engines,
    596          * whereas Xe_HP and beyond have bits representing present engines.
    597          * Invert the polarity on old platforms so that we can use common
    598          * handling below.
    599          */
    600         if (GRAPHICS_VERx100(xe) < 1250)
    601                 media_fuse = ~media_fuse;
    602 
    603         vdbox_mask = REG_FIELD_GET(GT_VDBOX_DISABLE_MASK, media_fuse);
    604         vebox_mask = REG_FIELD_GET(GT_VEBOX_DISABLE_MASK, media_fuse);
    605 
    606         for (i = XE_HW_ENGINE_VCS0, j = 0; i <= XE_HW_ENGINE_VCS7; ++i, ++j) {
    607                 if (!(gt->info.engine_mask & BIT(i)))
    608                         continue;
    609 
    610                 if (!(BIT(j) & vdbox_mask)) {
--> 611                         gt->info.engine_mask &= ~BIT(i);

This would only be an issue on 32bit builds...  The ->engine_mask is a
u64 but BIT() is unsigned long (32 bit in this case).  So this clears
out the top 32 bits.

I think that we don't actually need 64 flags, so we could just make
gt->info.engine_mask a u32.

    612                         drm_info(&xe->drm, "vcs%u fused off\n", j);
    613                 }
    614         }
    615 
    616         for (i = XE_HW_ENGINE_VECS0, j = 0; i <= XE_HW_ENGINE_VECS3; ++i, ++j) {
    617                 if (!(gt->info.engine_mask & BIT(i)))
    618                         continue;
    619 
    620                 if (!(BIT(j) & vebox_mask)) {
    621                         gt->info.engine_mask &= ~BIT(i);
    622                         drm_info(&xe->drm, "vecs%u fused off\n", j);
    623                 }
    624         }
    625 }

regards,
dan carpenter