linux-kernel - Re: [PATCH v3 3/3] i2c-ocores: sifive: add polling mode workaround for FU540-C000 SoC

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Date:   Thu, 16 May 2019 15:07:20 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Sagar Shrikant Kadam <sagar.kadam@...ive.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com, peter@...sgaard.com,
        palmer@...ive.com, paul.walmsley@...ive.com,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] i2c-ocores: sifive: add polling mode workaround
 for FU540-C000 SoC

On Thu, May 16, 2019 at 10:38:40AM +0530, Sagar Shrikant Kadam wrote:
> The i2c-ocore driver already has a polling mode interface.But it needs
> a workaround for FU540 Chipset on HiFive unleashed board (RevA00).
> There is an erratum in FU540 chip that prevents interrupt driven i2c
> transfers from working, and also the I2C controller's interrupt bit
> cannot be cleared if set, due to this the existing i2c polling mode
> interface added in mainline earlier doesn't work, and CPU stall's
> infinitely, when-ever i2c transfer is initiated.
> 
> Ref:previous polling mode support in mainline
> 
> 	commit 69c8c0c0efa8 ("i2c: ocores: add polling interface")
> 
> The workaround / fix under OCORES_FLAG_BROKEN_IRQ is particularly for
> FU540-COOO SoC.
> 
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@...ive.com>
> ---
>  drivers/i2c/busses/i2c-ocores.c | 34 ++++++++++++++++++++++++++++------
>  1 file changed, 28 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index aee1d86..00ee45c 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -27,6 +27,7 @@
>  #include <linux/jiffies.h>
>  
>  #define OCORES_FLAG_POLL BIT(0)
> +#define OCORES_FLAG_BROKEN_IRQ BIT(2) /* Broken IRQ in HiFive Unleashed */

Hi Sigar

BIT(1). Don't leave a gap.

	Andrew