[PATCH 5/7] spi: dw: Actually mask interrupts

[Sean Anderson]

On 2/15/22 11:16 AM, Niklas Cassel wrote:
> From: Sean Anderson <seanga2 at gmail.com>
> 
> The designware spi driver unconditionally uses polling.
> 
> The comment to spi_hw_init() also states that the function should disable
> interrupts.
> 
> According to the DesignWare DW_apb_ssi Databook, value 0xff in IMR enables
> all interrupts. Since we want to mask all interrupts write 0x0 instead.
> 
> On the canaan k210 board, pressing the reset button twice to reset the
> board will run u-boot. If u-boot boots Linux without having SPI interrupts
> masked, Linux will hang as soon as interrupts are enabled, because of an
> interrupt storm.
> 
> Properly masking the SPI interrupts in u-boot allows us to successfully
> boot Linux, even after resetting the board.
> 
> Fixes: 5bef6fd79f94 ("spi: Add designware master SPI DM driver used on SoCFPGA")
> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
> [Niklas: rewrite commit message]
> Signed-off-by: Niklas Cassel <niklas.cassel at wdc.com>
> ---
>   drivers/spi/designware_spi.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
> index f9b19a5ea4..47bea0b376 100644
> --- a/drivers/spi/designware_spi.c
> +++ b/drivers/spi/designware_spi.c
> @@ -266,7 +266,7 @@ static int dw_spi_of_to_plat(struct udevice *bus)
>   static void spi_hw_init(struct udevice *bus, struct dw_spi_priv *priv)
>   {
>   	dw_write(priv, DW_SPI_SSIENR, 0);
> -	dw_write(priv, DW_SPI_IMR, 0xff);
> +	dw_write(priv, DW_SPI_IMR, 0);
>   	dw_write(priv, DW_SPI_SSIENR, 1);
>   
>   	/*
> 
Reviewed-by: Sean Anderson <seanga2 at gmail.com>