linux-kernel - Re: [PATCH] i2c: tegra: Fix i2c-tegra DMA config option processing

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Message-ID: <20230804214902.entkn6xkklz5lh3h@intel.intel>
Date:   Fri, 4 Aug 2023 23:49:02 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Parker Newman <pnewman@...necttech.com>
Cc:     Laxman Dewangan <ldewangan@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: tegra: Fix i2c-tegra DMA config option processing

Hi Laxman and/or Dmitry,

On Thu, Aug 03, 2023 at 05:10:02PM +0000, Parker Newman wrote:
> 
> This patch fixes the Tegra DMA config option processing in the
> i2c-tegra driver.
> 
> Tegra processors prior to Tegra186 used APB DMA for I2C requiring
> CONFIG_TEGRA20_APB_DMA=y while Tegra186 and later use GPC DMA requiring
> CONFIG_TEGRA186_GPC_DMA=y.
> 
> The check for if the processor uses APB DMA is inverted and so the wrong
> DMA config options are checked.
> 
> This means if CONFIG_TEGRA20_APB_DMA=y but CONFIG_TEGRA186_GPC_DMA=n
> with a Tegra186 or later processor the driver will incorrectly think DMA is
> enabled and attempt to request DMA channels that will never be availible,
> leaving the driver in a perpetual EPROBE_DEFER state.
> 
> Signed-off-by: Parker Newman <pnewman@...necttech.com>
> ---
>  drivers/i2c/busses/i2c-tegra.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index bcbbf23aa530..dc6ed3a8d69e 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -442,7 +442,7 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
>     if (IS_VI(i2c_dev))
>         return 0;
> 
> -   if (!i2c_dev->hw->has_apb_dma) {
> +   if (i2c_dev->hw->has_apb_dma) {
>         if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA)) {
>             dev_dbg(i2c_dev->dev, "APB DMA support not enabled\n");
>             return 0;

Can I have your opinion here, please?

Andi