| From c3ccf357c3d75bd2924e049b6a991f7c0c111068 Mon Sep 17 00:00:00 2001 |
| From: Geert Uytterhoeven <geert+renesas@glider.be> |
| Date: Fri, 5 Aug 2016 10:17:52 +0200 |
| Subject: spi: sh-msiof: Avoid invalid clock generator parameters |
| |
| From: Geert Uytterhoeven <geert+renesas@glider.be> |
| |
| commit c3ccf357c3d75bd2924e049b6a991f7c0c111068 upstream. |
| |
| The conversion from a look-up table to a calculation for clock generator |
| parameters forgot to take into account that BRDV x 1/1 is valid only if |
| BRPS is x 1/1 or x 1/2, leading to undefined behavior (e.g. arbitrary |
| clock rates). |
| |
| This limitation is documented for the MSIOF module in all supported |
| SH/R-Mobile and R-Car Gen2/Gen3 ARM SoCs. |
| |
| Tested on r8a7791/koelsch and r8a7795/salvator-x. |
| |
| Fixes: 65d5665bb260b034 ("spi: sh-msiof: Update calculation of frequency dividing") |
| Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> |
| Signed-off-by: Mark Brown <broonie@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/spi/spi-sh-msiof.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/drivers/spi/spi-sh-msiof.c |
| +++ b/drivers/spi/spi-sh-msiof.c |
| @@ -263,6 +263,9 @@ static void sh_msiof_spi_set_clk_regs(st |
| |
| for (k = 0; k < ARRAY_SIZE(sh_msiof_spi_div_table); k++) { |
| brps = DIV_ROUND_UP(div, sh_msiof_spi_div_table[k].div); |
| + /* SCR_BRDV_DIV_1 is valid only if BRPS is x 1/1 or x 1/2 */ |
| + if (sh_msiof_spi_div_table[k].div == 1 && brps > 2) |
| + continue; |
| if (brps <= 32) /* max of brdv is 32 */ |
| break; |
| } |
