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drm/omap: Hide sparse warnings

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sparse reports:

drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:122:16: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:122:16:    expected void const volatile [noderef] __iomem *addr
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:122:16:    got unsigned int [usertype] *wa_dma_data
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:130:9: warning: incorrect type in argument 2 (different address spaces)
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:130:9:    expected void volatile [noderef] __iomem *addr
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:130:9:    got unsigned int [usertype] *wa_dma_data
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:414:9: warning: incorrect type in argument 1 (different address spaces)
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:414:9:    expected void const volatile [noderef] __iomem *addr
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c:414:9:    got unsigned int *

These come from pieces of code which do essentially:

p = dma_alloc_coherent()

dma_transfer_to_p()
readl(p)

writel(x, p)
dma_transfer_from_p()

I think we would do just fine without readl() and writel(), accessing
the memory without any extras, but ensuring that the necessary barriers
are in place. But this code is for a legacy platform, has been working
for ages, and it's doing work-arounds for hardware issues, and those
hardware issues are very difficult to trigger... So I would just rather
leave the code be as it is now.

However, the warnings are not nice. Hide the warnings by a (__iomem void
*) typecast.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407311737.VsJ0Sr1w-lkp@intel.com/
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240806-omapdrm-misc-fixes-v1-2-15d31aea0831@ideasonboard.com
This commit is contained in:
Tomi Valkeinen 2024-08-06 16:50:28 +03:00
parent a88fee2d67
commit 0d76cb1148
1 changed files with 3 additions and 3 deletions
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6
drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
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@ -119,7 +119,7 @@ static u32 dmm_read_wa(struct dmm *dmm, u32 reg)
* earlier than the DMA finished writing the value to memory.
*/
rmb();
return readl(dmm->wa_dma_data);
return readl((__iomem void *)dmm->wa_dma_data);
}
static void dmm_write_wa(struct dmm *dmm, u32 val, u32 reg)
@ -127,7 +127,7 @@ static void dmm_write_wa(struct dmm *dmm, u32 val, u32 reg)
dma_addr_t src, dst;
int r;
writel(val, dmm->wa_dma_data);
writel(val, (__iomem void *)dmm->wa_dma_data);
/*
* As per i878 workaround, the DMA is used to access the DMM registers.
* Make sure that the writel is not moved by the compiler or the CPU, so
@ -411,7 +411,7 @@ static int dmm_txn_commit(struct dmm_txn *txn, bool wait)
*/
/* read back to ensure the data is in RAM */
readl(&txn->last_pat->next_pa);
readl((__iomem void *)&txn->last_pat->next_pa);
/* write to PAT_DESCR to clear out any pending transaction */
dmm_write(dmm, 0x0, reg[PAT_DESCR][engine->id]);