[PATCH v3 2/2] mtd: spi-nor: parse Serial Flash Discoverable Parameters (SFDP) tables

[Geert Uytterhoeven]

Hi Cyrille, Boris,

On Mon, Jun 26, 2017 at 3:10 PM, Cyrille Pitchen
<cyrille.pitchen at microchip.com> wrote:
> This patch adds support to the JESD216 rev B standard and parses the SFDP
> tables to dynamically initialize the 'struct spi_nor_flash_parameter'.
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen at microchip.com>

This patch, which is now commit f384b352cbf0310f ("mtd: spi-nor: parse
Serial Flash
Discoverable Parameters (SFDP) tables") in -next, and which was included in the
"MTD updates for 4.14" pull request, broke QSPI FLASH on R-Car Gen2.

E.g. on r8a7794/alt, the following warning is printed with
CONFIG_DMA_API_DEBUG=y:

    WARNING: CPU: 1 PID: 1 at lib/dma-debug.c:1188 check_for_stack+0xcc/0x114
    rcar-dmac e6720000.dma-controller: DMA-API: device driver maps
memory from stack [addr=ef43dad8]
    Modules linked in:
    CPU: 1 PID: 1 Comm: swapper/0 Not tainted
4.13.0-rcar2-initrd-00404-g3d49bfdcf5ecd040 #76
    Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
    [<c020e664>] (unwind_backtrace) from [<c020a13c>] (show_stack+0x10/0x14)
    [<c020a13c>] (show_stack) from [<c06a5c50>] (dump_stack+0x7c/0x9c)
    [<c06a5c50>] (dump_stack) from [<c021ef58>] (__warn+0xcc/0xfc)
    [<c021ef58>] (__warn) from [<c021efbc>] (warn_slowpath_fmt+0x34/0x44)
    [<c021efbc>] (warn_slowpath_fmt) from [<c0403228>]
(check_for_stack+0xcc/0x114)
    [<c0403228>] (check_for_stack) from [<c0403a9c>]
(debug_dma_map_sg+0xe4/0x168)
    [<c0403a9c>] (debug_dma_map_sg) from [<c04cd7b8>] (spi_map_buf+0x2f4/0x32c)
    [<c04cd7b8>] (spi_map_buf) from [<c04ce560>]
(__spi_pump_messages+0x430/0x4d8)
    [<c04ce560>] (__spi_pump_messages) from [<c04ce77c>]
(__spi_sync+0x168/0x194)
    [<c04ce77c>] (__spi_sync) from [<c04ce7cc>] (spi_sync+0x24/0x3c)
    [<c04ce7cc>] (spi_sync) from [<c04c97fc>] (m25p80_read+0x2e4/0x300)
    [<c04c97fc>] (m25p80_read) from [<c04c99d8>] (spi_nor_read_sfdp+0x58/0xa8)
    [<c04c99d8>] (spi_nor_read_sfdp) from [<c04c9fc8>]
(spi_nor_init_params+0x2e8/0x5f4)
    [<c04c9fc8>] (spi_nor_init_params) from [<c04cb510>]
(spi_nor_scan+0xc4/0x830)
    [<c04cb510>] (spi_nor_scan) from [<c04c9928>] (m25p_probe+0x110/0x168)
    [<c04c9928>] (m25p_probe) from [<c04cce0c>] (spi_drv_probe+0x84/0xa0)
    [<c04cce0c>] (spi_drv_probe) from [<c0470f80>]
(driver_probe_device+0x150/0x2d0)
    [<c0470f80>] (driver_probe_device) from [<c046f7fc>]
(bus_for_each_drv+0x84/0x94)
    [<c046f7fc>] (bus_for_each_drv) from [<c0470d98>]
(__device_attach+0x88/0xfc)
    [<c0470d98>] (__device_attach) from [<c0470450>]
(bus_probe_device+0x28/0x80)
    [<c0470450>] (bus_probe_device) from [<c046ebac>] (device_add+0x3f8/0x50c)
    [<c046ebac>] (device_add) from [<c04cef54>] (spi_add_device+0xd0/0x14c)
    [<c04cef54>] (spi_add_device) from [<c04cf308>]
(of_register_spi_device+0x200/0x2f4)
    [<c04cf308>] (of_register_spi_device) from [<c04cf878>]
(spi_register_controller+0x47c/0x5e4)
    [<c04cf878>] (spi_register_controller) from [<c04cfa10>]
(devm_spi_register_controller+0x30/0x6c)
    [<c04cfa10>] (devm_spi_register_controller) from [<c04d190c>]
(rspi_probe+0x258/0x404)
    [<c04d190c>] (rspi_probe) from [<c0472780>] (platform_drv_probe+0x50/0xa0)
    [<c0472780>] (platform_drv_probe) from [<c0470f80>]
(driver_probe_device+0x150/0x2d0)
    [<c0470f80>] (driver_probe_device) from [<c0471180>]
(__driver_attach+0x80/0xa4)
    [<c0471180>] (__driver_attach) from [<c046f740>]
(bus_for_each_dev+0x6c/0x90)
    [<c046f740>] (bus_for_each_dev) from [<c047064c>]
(bus_add_driver+0xc8/0x1e4)
    [<c047064c>] (bus_add_driver) from [<c0471a14>] (driver_register+0x9c/0xe0)
    [<c0471a14>] (driver_register) from [<c0201718>]
(do_one_initcall+0xa8/0x14c)
    [<c0201718>] (do_one_initcall) from [<c0c00d84>]
(kernel_init_freeable+0x114/0x:
    [<c0c00d84>] (kernel_init_freeable) from [<c06b6244>]
(kernel_init+0x8/0x10c)
    [<c06b6244>] (kernel_init) from [<c0206b68>] (ret_from_fork+0x14/0x2c)

This leads to the SPI FLASH size being misdetected as zero:

    -m25p80 spi0.0: s25fl512s (65536 Kbytes)
    +m25p80 spi0.0: s25fl512s (0 Kbytes)
     3 ofpart partitions found on MTD device spi0.0
     Creating 3 MTD partitions on "spi0.0":
     0x000000000000-0x000000040000 : "loader"
    +mtd: partition "loader" is out of reach -- disabled
     0x000000040000-0x000000080000 : "system"
    +mtd: partition "system" is out of reach -- disabled
     0x000000080000-0x000004000000 : "user"
    +mtd: partition "user" is out of reach -- disabled

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds