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+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <[email protected]>
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+Subject: [PATCH] mtd: m25p80: use single SPI message for writing data
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+MIME-Version: 1.0
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+Content-Type: text/plain; charset=UTF-8
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+Content-Transfer-Encoding: 8bit
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+
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+On all 3 tested Northstar devices with following flash memories:
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+mx25l6405d (8192 Kbytes)
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+mx25l12805d (16384 Kbytes)
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+mx25l25635e (32768 Kbytes)
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+I noticed writing to be broken. Not a single bit was changed leaving all
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+bytes set to 0xff.
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+
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+This is most likely some problem related to the SPI controller or its
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+driver. Using a single SPI message seems to workaround this. Of course
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+it's not perfect solution as copying whole data into a new buffer makes
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+writing slower.
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+
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+Signed-off-by: Rafał Miłecki <[email protected]>
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+---
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+
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+--- a/drivers/mtd/devices/m25p80.c
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++++ b/drivers/mtd/devices/m25p80.c
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+@@ -78,29 +78,30 @@ static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
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+ {
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+ struct m25p *flash = nor->priv;
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+ struct spi_device *spi = flash->spi;
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++ u8 *command = kzalloc(MAX_CMD_SIZE + len, GFP_KERNEL);
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+ struct spi_transfer t[2] = {};
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+ struct spi_message m;
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+ int cmd_sz = m25p_cmdsz(nor);
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++ int i;
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+
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+ spi_message_init(&m);
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+
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+ if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
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+ cmd_sz = 1;
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+
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+- flash->command[0] = nor->program_opcode;
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+- m25p_addr2cmd(nor, to, flash->command);
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++ command[0] = nor->program_opcode;
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++ m25p_addr2cmd(nor, to, command);
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++ memcpy(&command[cmd_sz], buf, len);
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+
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+- t[0].tx_buf = flash->command;
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+- t[0].len = cmd_sz;
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++ t[0].tx_buf = command;
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++ t[0].len = cmd_sz + len;
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+ spi_message_add_tail(&t[0], &m);
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+
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+- t[1].tx_buf = buf;
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+- t[1].len = len;
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+- spi_message_add_tail(&t[1], &m);
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+-
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+ spi_sync(spi, &m);
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+
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+ *retlen += m.actual_length - cmd_sz;
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++
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++ kfree(command);
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+ }
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+
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+ static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)
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Rafał Miłecki