target/linux/layerscape/patches-4.4/1107-mtd-fsl-quadspi-disable-AHB-buffer-prefetch.patch

   1 From 50aac689d5be0a086f076cd4bc8b14ee0b9ab995 Mon Sep 17 00:00:00 2001
   2 From: Yunhui Cui <yunhui.cui@nxp.com>
   3 Date: Tue, 8 Mar 2016 14:38:52 +0800
   4 Subject: [PATCH 107/113] mtd: fsl-quadspi: disable AHB buffer prefetch
   5
   6 A-009282: QuadSPI: QuadSPI data pre-fetch can result in incorrect data
   7 Affects: QuadSPI
   8 Description: With AHB buffer prefetch enabled, the QuadSPI may return
   9 incorrect data on the AHB
  10 interface. The buffer pre-fetch is enabled if the fetch size as
  11 configured either in the LUT or in
  12 the BUFxCR register is greater than 8 bytes.
  13 Impact: Only 64 bit read allowed.
  14 Workaround: Keep the read data size to 64 bits (8 Bytes), which disables
  15 the prefetch on the AHB buffer,
  16 and prevents this issue from occurring.
  17
  18 Signed-off-by: Yunhui Cui <yunhui.cui@nxp.com>
  19 ---
  20  drivers/mtd/spi-nor/fsl-quadspi.c |   29 +++++++++++++++++++++++------
  21  1 file changed, 23 insertions(+), 6 deletions(-)
  22
  23 --- a/drivers/mtd/spi-nor/fsl-quadspi.c
  24 +++ b/drivers/mtd/spi-nor/fsl-quadspi.c
  25 @@ -794,19 +794,36 @@ static void fsl_qspi_init_abh_read(struc
  26  {
  27         void __iomem *base = q->iobase;
  28         int seqid;
  29 +       const struct fsl_qspi_devtype_data *devtype_data = q->devtype_data;
  30
  31         /* AHB configuration for access buffer 0/1/2 .*/
  32         qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF0CR);
  33         qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF1CR);
  34         qspi_writel(q, QUADSPI_BUFXCR_INVALID_MSTRID, base + QUADSPI_BUF2CR);
  35 +
  36         /*
  37 -        * Set ADATSZ with the maximum AHB buffer size to improve the
  38 -        * read performance.
  39 +        * Errata: A-009282: QuadSPI data prefetch may result in incorrect data
  40 +        * Workaround: Keep the read data size to 64 bits (8 bytes).
  41 +        * This disables the prefetch on the AHB buffer and
  42 +        * prevents this issue from occurring.
  43          */
  44 -       qspi_writel(q, QUADSPI_BUF3CR_ALLMST_MASK |
  45 -                       ((q->devtype_data->ahb_buf_size / 8)
  46 -                       << QUADSPI_BUF3CR_ADATSZ_SHIFT),
  47 -                       base + QUADSPI_BUF3CR);
  48 +       if (devtype_data->devtype == FSL_QUADSPI_LS2080A ||
  49 +           devtype_data->devtype == FSL_QUADSPI_LS1021A) {
  50 +
  51 +               qspi_writel(q, QUADSPI_BUF3CR_ALLMST_MASK |
  52 +                               (1 << QUADSPI_BUF3CR_ADATSZ_SHIFT),
  53 +                               base + QUADSPI_BUF3CR);
  54 +
  55 +       } else {
  56 +               /*
  57 +                * Set ADATSZ with the maximum AHB buffer size to improve the
  58 +                * read performance.
  59 +               */
  60 +               qspi_writel(q, QUADSPI_BUF3CR_ALLMST_MASK |
  61 +                               ((q->devtype_data->ahb_buf_size / 8)
  62 +                               << QUADSPI_BUF3CR_ADATSZ_SHIFT),
  63 +                               base + QUADSPI_BUF3CR);
  64 +       }
  65
  66         /* We only use the buffer3 */
  67         qspi_writel(q, 0, base + QUADSPI_BUF0IND);