linux-kernel - Re: [PATCH v1 2/7] net: ipa: endpoint: Don't read unexistant register on IPAv3.1

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Date:   Mon, 1 Mar 2021 20:05:07 -0600
From:   Alex Elder <elder@...e.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>, elder@...nel.org
Cc:     bjorn.andersson@...aro.org, agross@...nel.org, davem@...emloft.net,
        kuba@...nel.org, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, konrad.dybcio@...ainline.org,
        marijn.suijten@...ainline.org, phone-devel@...r.kernel.org
Subject: Re: [PATCH v1 2/7] net: ipa: endpoint: Don't read unexistant register
 on IPAv3.1

On 2/11/21 11:50 AM, AngeloGioacchino Del Regno wrote:
> On IPAv3.1 there is no such FLAVOR_0 register so it is impossible
> to read tx/rx channel masks and we have to rely on the correctness
> on the provided configuration.

This works, and is simple.

I think I would rather populate the available mask here
with a mask containing the actual version-specific available
endpoints.  On the other hand, looking at the downstream code,
it looks like almost any of these endpoints could be used.

So, while I don't know for sure the all-1's value here is
*correct*, it's more of a validation check anyway, so it's
probably fine

					-Alex

> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
> ---
>  drivers/net/ipa/ipa_endpoint.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
> index 06d8aa34276e..10c477e1bb90 100644
> --- a/drivers/net/ipa/ipa_endpoint.c
> +++ b/drivers/net/ipa/ipa_endpoint.c
> @@ -1659,6 +1659,15 @@ int ipa_endpoint_config(struct ipa *ipa)
>  	u32 max;
>  	u32 val;
>  
> +	/* Some IPA versions don't provide a FLAVOR register and we cannot
> +	 * check the rx/tx masks hence we have to rely on the correctness
> +	 * of the provided configuration.
> +	 */
> +	if (ipa->version == IPA_VERSION_3_1) {
> +		ipa->available = U32_MAX;
> +		return 0;
> +	}
> +
>  	/* Find out about the endpoints supplied by the hardware, and ensure
>  	 * the highest one doesn't exceed the number we support.
>  	 */
>