bcm53xx: replace SPI revert with a fix sent upstream

Instead of reverting whole commit it's enough to just revert a single
line change. It seems the real problem with the regressing commit was a
bump of read chunk size. Switching back to 256 B chunks is enough to fix
the problem/regression.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
(cherry picked from commit 92de28b751a473655fd0cf3d3a8b81ca1d27d758)

2 files changed, 42 insertions, 146 deletions

diff --git a/target/linux/bcm53xx/patches-4.14/180-spi-bcm-qspi-switch-back-to-reading-flash-using-smal.patch b/target/linux/bcm53xx/patches-4.14/180-spi-bcm-qspi-switch-back-to-reading-flash-using-smal.patch
new file mode 100644
index 0000000000..4b3056591e
--- /dev/null
+++ b/target/linux/bcm53xx/patches-4.14/180-spi-bcm-qspi-switch-back-to-reading-flash-using-smal.patch
@@ -0,0 +1,42 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 11 Oct 2018 09:07:31 +0200
+Subject: [PATCH FIX] spi: bcm-qspi: switch back to reading flash using smaller
+ chunks
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Fixing/optimizing bcm_qspi_bspi_read() performance introduced two
+changes:
+1) It added a loop to read all requested data using multiple BSPI ops.
+2) It bumped max size of a single BSPI block request from 256 to 512 B.
+
+The later change resulted in occasional BSPI timeouts causing a
+regression.
+
+For some unknown reason hardware doesn't always handle reads as expected
+when using 512 B chunks. In such cases it may happen that BSPI returns
+amount of requested bytes without the last 1-3 ones. It provides the
+remaining bytes later but doesn't raise an interrupt until another LR
+start.
+
+Switching back to 256 B reads fixes that problem and regression.
+
+Fixes: 345309fa7c0c ("spi: bcm-qspi: Fix bcm_qspi_bspi_read() performance")
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Cc: stable@vger.kernel.org # 4.11+
+---
+ drivers/spi/spi-bcm-qspi.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/spi/spi-bcm-qspi.c
++++ b/drivers/spi/spi-bcm-qspi.c
+@@ -88,7 +88,7 @@
+ #define BSPI_BPP_MODE_SELECT_MASK		BIT(8)
+ #define BSPI_BPP_ADDR_SELECT_MASK		BIT(16)
+ 
+-#define BSPI_READ_LENGTH			512
++#define BSPI_READ_LENGTH			256
+ 
+ /* MSPI register offsets */
+ #define MSPI_SPCR0_LSB				0x000
diff --git a/target/linux/bcm53xx/patches-4.14/800-Revert-spi-bcm-qspi-Fix-bcm_qspi_bspi_read-performan.patch b/target/linux/bcm53xx/patches-4.14/800-Revert-spi-bcm-qspi-Fix-bcm_qspi_bspi_read-performan.patch
deleted file mode 100644
index 64f971d349..0000000000
--- a/target/linux/bcm53xx/patches-4.14/800-Revert-spi-bcm-qspi-Fix-bcm_qspi_bspi_read-performan.patch
+++ /dev/null
@@ -1,146 +0,0 @@
-From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
-Subject: [PATCH] Revert "spi: bcm-qspi: Fix bcm_qspi_bspi_read() performance"
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-This reverts commit 345309fa7c0c9206a5344d379b174499952d79d9.
-
-BSPI reads became unstable starting with above commit. There are BSPI
-timeouts like this:
-[   15.637809] bcm_iproc 18029200.spi: timeout waiting for BSPI
-(...)
-[   15.997809] bcm_iproc 18029200.spi: timeout waiting for BSPI
-which cause filesystem stability problems.
-
-Before above commit every time that bcm_qspi_bspi_lr_l2_isr() called
-bcm_qspi_bspi_lr_l2_isr() it was resulting in bspi_rf_msg_len becoming
-0.
-With that change it's not the case anymore which suggests there may be
-some bug around that code.
-
-It has changed and the new behavior seems to be causing problems.
-
-Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
----
-
---- a/drivers/spi/spi-bcm-qspi.c
-+++ b/drivers/spi/spi-bcm-qspi.c
-@@ -88,7 +88,7 @@
- #define BSPI_BPP_MODE_SELECT_MASK		BIT(8)
- #define BSPI_BPP_ADDR_SELECT_MASK		BIT(16)
- 
--#define BSPI_READ_LENGTH			512
-+#define BSPI_READ_LENGTH			256
- 
- /* MSPI register offsets */
- #define MSPI_SPCR0_LSB				0x000
-@@ -806,7 +806,7 @@ static int bcm_qspi_bspi_flash_read(stru
- 				    struct spi_flash_read_message *msg)
- {
- 	struct bcm_qspi *qspi = spi_master_get_devdata(spi->master);
--	u32 addr = 0, len, rdlen, len_words;
-+	u32 addr = 0, len, len_words;
- 	int ret = 0;
- 	unsigned long timeo = msecs_to_jiffies(100);
- 	struct bcm_qspi_soc_intc *soc_intc = qspi->soc_intc;
-@@ -819,7 +819,7 @@ static int bcm_qspi_bspi_flash_read(stru
- 	bcm_qspi_write(qspi, MSPI, MSPI_WRITE_LOCK, 0);
- 
- 	/*
--	 * when using flex mode we need to send
-+	 * when using flex mode mode we need to send
- 	 * the upper address byte to bspi
- 	 */
- 	if (bcm_qspi_bspi_ver_three(qspi) == false) {
-@@ -833,56 +833,47 @@ static int bcm_qspi_bspi_flash_read(stru
- 	else
- 		addr = msg->from & 0x00ffffff;
- 
-+	/* set BSPI RAF buffer max read length */
-+	len = msg->len;
-+	if (len > BSPI_READ_LENGTH)
-+		len = BSPI_READ_LENGTH;
-+
- 	if (bcm_qspi_bspi_ver_three(qspi) == true)
- 		addr = (addr + 0xc00000) & 0xffffff;
- 
--	/*
--	 * read into the entire buffer by breaking the reads
--	 * into RAF buffer read lengths
--	 */
--	len = msg->len;
-+	reinit_completion(&qspi->bspi_done);
-+	bcm_qspi_enable_bspi(qspi);
-+	len_words = (len + 3) >> 2;
-+	qspi->bspi_rf_msg = msg;
-+	qspi->bspi_rf_msg_status = 0;
- 	qspi->bspi_rf_msg_idx = 0;
-+	qspi->bspi_rf_msg_len = len;
-+	dev_dbg(&qspi->pdev->dev, "bspi xfr addr 0x%x len 0x%x", addr, len);
- 
--	do {
--		if (len > BSPI_READ_LENGTH)
--			rdlen = BSPI_READ_LENGTH;
--		else
--			rdlen = len;
--
--		reinit_completion(&qspi->bspi_done);
--		bcm_qspi_enable_bspi(qspi);
--		len_words = (rdlen + 3) >> 2;
--		qspi->bspi_rf_msg = msg;
--		qspi->bspi_rf_msg_status = 0;
--		qspi->bspi_rf_msg_len = rdlen;
--		dev_dbg(&qspi->pdev->dev,
--			"bspi xfr addr 0x%x len 0x%x", addr, rdlen);
--		bcm_qspi_write(qspi, BSPI, BSPI_RAF_START_ADDR, addr);
--		bcm_qspi_write(qspi, BSPI, BSPI_RAF_NUM_WORDS, len_words);
--		bcm_qspi_write(qspi, BSPI, BSPI_RAF_WATERMARK, 0);
--		if (qspi->soc_intc) {
--			/*
--			 * clear soc MSPI and BSPI interrupts and enable
--			 * BSPI interrupts.
--			 */
--			soc_intc->bcm_qspi_int_ack(soc_intc, MSPI_BSPI_DONE);
--			soc_intc->bcm_qspi_int_set(soc_intc, BSPI_DONE, true);
--		}
-+	bcm_qspi_write(qspi, BSPI, BSPI_RAF_START_ADDR, addr);
-+	bcm_qspi_write(qspi, BSPI, BSPI_RAF_NUM_WORDS, len_words);
-+	bcm_qspi_write(qspi, BSPI, BSPI_RAF_WATERMARK, 0);
-+
-+	if (qspi->soc_intc) {
-+		/*
-+		 * clear soc MSPI and BSPI interrupts and enable
-+		 * BSPI interrupts.
-+		 */
-+		soc_intc->bcm_qspi_int_ack(soc_intc, MSPI_BSPI_DONE);
-+		soc_intc->bcm_qspi_int_set(soc_intc, BSPI_DONE, true);
-+	}
- 
--		/* Must flush previous writes before starting BSPI operation */
--		mb();
--		bcm_qspi_bspi_lr_start(qspi);
--		if (!wait_for_completion_timeout(&qspi->bspi_done, timeo)) {
--			dev_err(&qspi->pdev->dev, "timeout waiting for BSPI\n");
--			ret = -ETIMEDOUT;
--			break;
--		}
-+	/* Must flush previous writes before starting BSPI operation */
-+	mb();
- 
--		/* set msg return length */
--		msg->retlen += rdlen;
--		addr += rdlen;
--		len -= rdlen;
--	} while (len);
-+	bcm_qspi_bspi_lr_start(qspi);
-+	if (!wait_for_completion_timeout(&qspi->bspi_done, timeo)) {
-+		dev_err(&qspi->pdev->dev, "timeout waiting for BSPI\n");
-+		ret = -ETIMEDOUT;
-+	} else {
-+		/* set the return length for the caller */
-+		msg->retlen = len;
-+	}
- 
- 	return ret;
- }