iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h
new file mode 100644
index 000000000..08e0e3ffa
--- /dev/null
+++ b/include/drm/drm_cache.h
@@ -0,0 +1,88 @@
+/**************************************************************************
+ *
+ * Copyright 2009 Red Hat Inc.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ *
+ **************************************************************************/
+/*
+ * Authors:
+ * Dave Airlie <airlied@redhat.com>
+ */
+
+#ifndef _DRM_CACHE_H_
+#define _DRM_CACHE_H_
+
+#include <linux/scatterlist.h>
+
+struct iosys_map;
+
+void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
+void drm_clflush_sg(struct sg_table *st);
+void drm_clflush_virt_range(void *addr, unsigned long length);
+bool drm_need_swiotlb(int dma_bits);
+
+
+static inline bool drm_arch_can_wc_memory(void)
+{
+#if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
+	return false;
+#elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON64)
+	return false;
+#elif defined(CONFIG_ARM) || defined(CONFIG_ARM64)
+	/*
+	 * The DRM driver stack is designed to work with cache coherent devices
+	 * only, but permits an optimization to be enabled in some cases, where
+	 * for some buffers, both the CPU and the GPU use uncached mappings,
+	 * removing the need for DMA snooping and allocation in the CPU caches.
+	 *
+	 * The use of uncached GPU mappings relies on the correct implementation
+	 * of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU
+	 * will use cached mappings nonetheless. On x86 platforms, this does not
+	 * seem to matter, as uncached CPU mappings will snoop the caches in any
+	 * case. However, on ARM and arm64, enabling this optimization on a
+	 * platform where NoSnoop is ignored results in loss of coherency, which
+	 * breaks correct operation of the device. Since we have no way of
+	 * detecting whether NoSnoop works or not, just disable this
+	 * optimization entirely for ARM and arm64.
+	 */
+	return false;
+#elif defined(CONFIG_LOONGARCH)
+	/*
+	 * LoongArch maintains cache coherency in hardware, but its WUC attribute
+	 * (Weak-ordered UnCached, which is similar to WC) is out of the scope of
+	 * cache coherency machanism. This means WUC can only used for write-only
+	 * memory regions.
+	 */
+	return false;
+#else
+	return true;
+#endif
+}
+
+void drm_memcpy_init_early(void);
+
+void drm_memcpy_from_wc(struct iosys_map *dst,
+			const struct iosys_map *src,
+			unsigned long len);
+#endif