Merge tag 'spi-nor/for-5.19' into mtd/next

SPI NOR core changes:
- Read back written SR value to make sure the write was done correctly.
- Introduce a common function for Read ID that manufacturer drivers can
  use to verify the Octal DTR switch worked correctly.
- Add helpers for read/write any register commands so manufacturer
  drivers don't open code it every time.
- Clarify rdsr dummy cycles documentation.
- Add debugfs entry to expose internal flash parameters and state.

SPI NOR manufacturer drivers changes:
- Add support for Winbond W25Q512NW-IM, and Eon EN25QH256A.
- Move spi_nor_write_ear() to Winbond module since only Winbond flashes
  use it.
- Rework Micron and Cypress Octal DTR enable methods to improve
  readability.
- Use the common Read ID function to verify switch to Octal DTR mode for
  Micron and Cypress flashes.
- Skip polling status on volatile register writes for Micron and Cypress
  flashes since the operation is instant.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 71efacb90965..3d215d9dec43 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -439,7 +439,16 @@ int hv_ringbuffer_read(struct vmbus_channel *channel,
 static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
 {
 	u32 priv_read_loc = rbi->priv_read_index;
-	u32 write_loc = READ_ONCE(rbi->ring_buffer->write_index);
+	u32 write_loc;
+
+	/*
+	 * The Hyper-V host writes the packet data, then uses
+	 * store_release() to update the write_index.  Use load_acquire()
+	 * here to prevent loads of the packet data from being re-ordered
+	 * before the read of the write_index and potentially getting
+	 * stale data.
+	 */
+	write_loc = virt_load_acquire(&rbi->ring_buffer->write_index);
 
 	if (write_loc >= priv_read_loc)
 		return write_loc - priv_read_loc;