Re: [PATCH 1/2] hwrng: iproc-rng200: Fix disable of the block.

Matthias Brugger
2020-12-18T10:51:22Z

On 14/12/2020 18:45, Scott Branden wrote:
>
>
> On 2020-12-14 8:04 a.m., matthias.bgg@kernel.org wrote:
>> From: Matthias Brugger <mbrugger@suse.com>
>>
>> When trying to disable the block we bitwise or the control
>> register with value zero. This will leave the block always turned on.
>> Fix this by setting the corresponding bit to zero.
>>
>> Fixes: c83d45d5685f ("hwrng: iproc-rng200 - Add Broadcom IPROC RNG driver")
> Commit message needs to be re-written.
> I don't think this is an actual fix as the ~RNG_CTL_RNG_RBGEN_MASK already zeros the bit.  This is just a code change, which is fine because it makes things clearer

Right, I'll reword it.

>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>> ---
>>
>> drivers/char/hw_random/iproc-rng200.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/char/hw_random/iproc-rng200.c b/drivers/char/hw_random/iproc-rng200.c
>> index 01583faf9893..e106ce3c0146 100644
>> --- a/drivers/char/hw_random/iproc-rng200.c
>> +++ b/drivers/char/hw_random/iproc-rng200.c
>> @@ -28,7 +28,6 @@
>> #define RNG_CTRL_OFFSET 0x00
>> #define RNG_CTRL_RNG_RBGEN_MASK 0x00001FFF
>> #define RNG_CTRL_RNG_RBGEN_ENABLE 0x00000001
>> -#define RNG_CTRL_RNG_RBGEN_DISABLE 0x00000000
>>
>> #define RNG_SOFT_RESET_OFFSET 0x04
>> #define RNG_SOFT_RESET 0x00000001
>> @@ -61,7 +60,7 @@ static void iproc_rng200_restart(void __iomem *rng_base)
>> /* Disable RBG */
>> val = ioread32(rng_base + RNG_CTRL_OFFSET);
>> val &= ~RNG_CTRL_RNG_RBGEN_MASK;
> This mask will already zero the enable bit.
>> - val |= RNG_CTRL_RNG_RBGEN_DISABLE;
>> + val &= ~RNG_CTRL_RNG_RBGEN_ENABLE;

Correct, so no need for this extra line. I'll delete it.

>> iowrite32(val, rng_base + RNG_CTRL_OFFSET);
>>
>> /* Clear all interrupt status */
>> @@ -174,7 +173,7 @@ static void iproc_rng200_cleanup(struct hwrng *rng)
>> /* Disable RNG hardware */
>> val = ioread32(priv->base + RNG_CTRL_OFFSET);
>> val &= ~RNG_CTRL_RNG_RBGEN_MASK;
>> - val |= RNG_CTRL_RNG_RBGEN_DISABLE;
>> + val &= ~RNG_CTRL_RNG_RBGEN_ENABLE;
>> iowrite32(val, priv->base + RNG_CTRL_OFFSET);
>> }
>>