Re: [PATCH v2 05/10] mtd: rawnand: brcmnand: Add BCMBCA read data bus interface

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Hi,

On 01/18/2024 09:36 PM, Dan Carpenter wrote:
On Thu, Jan 18, 2024 at 11:53:51AM -0800, dregan@xxxxxxxxxxxx wrote:
diff --git a/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c b/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
index 3e2f3b79788d..e97e13ae246c 100644
--- a/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
+++ b/drivers/mtd/nand/raw/brcmnand/bcmbca_nand.c
@@ -26,6 +26,18 @@ enum {
  	BCMBCA_CTLRDY		= BIT(4),
  };
+#if defined(CONFIG_ARM64)
+#define ALIGN_REQ		8
+#else
+#define ALIGN_REQ		4
+#endif
+
+static inline bool bcmbca_nand_is_buf_aligned(void *flash_cache,  void *buffer)
+{
+	return IS_ALIGNED((uintptr_t)buffer, ALIGN_REQ) &&
+				IS_ALIGNED((uintptr_t)flash_cache, ALIGN_REQ);
+}
+
  static bool bcmbca_nand_intc_ack(struct brcmnand_soc *soc)
  {
  	struct bcmbca_nand_soc *priv =
@@ -56,6 +68,20 @@ static void bcmbca_nand_intc_set(struct brcmnand_soc *soc, bool en)
  	brcmnand_writel(val, mmio);
  }
+static void bcmbca_read_data_bus(struct brcmnand_soc *soc,
+				 void __iomem *flash_cache,  u32 *buffer, int fc_words)
+{
+	/*
+	 * memcpy can do unaligned aligned access depending on source
+	 * and dest address, which is incompatible with nand cache. Fallback
+	 * to the memcpy for io version
+	 */
+	if (bcmbca_nand_is_buf_aligned((void *)flash_cache, buffer))
+		memcpy((void *)buffer, (void *)flash_cache, fc_words * 4);
+	else
+		memcpy_fromio((void *)buffer, flash_cache, fc_words * 4);
+}

This comment is confusing or maybe the if statement is reversed...
We're falling back to memcpy_fromio() for the unaligned accesses but the
comment says we're falling back to memcpy().

Yes that's a typo. Fallback to memcpy_fromio when unalgined. Will update the comments in v3. Thanks!

regards,
dan carpenter

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