linux-kernel - Re: [PATCH v1 1/7] net: ipa: Add support for IPA v3.1 with GSI v1.0

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Message-ID: <7fdac2c4-b599-6db5-21e2-676c850edcf8@ieee.org>
Date:   Mon, 1 Mar 2021 20:05:02 -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 1/7] net: ipa: Add support for IPA v3.1 with GSI v1.0

On 2/11/21 11:50 AM, AngeloGioacchino Del Regno wrote:
> In preparation for adding support for the MSM8998 SoC's IPA,
> add the necessary bits for IPA version 3.1 featuring GSI 1.0,
> found on at least MSM8998.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>

Overall, this looks good.  As I mentioned, I've
implemented a very similar set of changes in my
private development tree.  It's part of a much
larger set of changes intended to allow many
IPA versions to be supported.

A few minor comments, below.

					-Alex

> ---
>  drivers/net/ipa/gsi.c          |  8 ++++----
>  drivers/net/ipa/ipa_endpoint.c | 17 +++++++++--------
>  drivers/net/ipa/ipa_main.c     |  8 ++++++--
>  drivers/net/ipa/ipa_reg.h      |  3 +++
>  drivers/net/ipa/ipa_version.h  |  1 +
>  5 files changed, 23 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
> index 14d9a791924b..6315336b3ca8 100644
> --- a/drivers/net/ipa/gsi.c
> +++ b/drivers/net/ipa/gsi.c
> @@ -794,14 +794,14 @@ static void gsi_channel_program(struct gsi_channel *channel, bool doorbell)
>  
>  	/* Max prefetch is 1 segment (do not set MAX_PREFETCH_FMASK) */
>  
> -	/* We enable the doorbell engine for IPA v3.5.1 */
> -	if (gsi->version == IPA_VERSION_3_5_1 && doorbell)
> +	/* We enable the doorbell engine for IPA v3.x */
> +	if (gsi->version < IPA_VERSION_4_0 && doorbell)

My version:
        if (gsi->version < IPA_VERSION_4_0 && doorbell)

So... You're doing the right thing.  Almost all changes I made
like this were identical to yours; others were (I think all)
equivalent.

>  		val |= USE_DB_ENG_FMASK;
>  
>  	/* v4.0 introduces an escape buffer for prefetch.  We use it
>  	 * on all but the AP command channel.
>  	 */
> -	if (gsi->version != IPA_VERSION_3_5_1 && !channel->command) {
> +	if (gsi->version >= IPA_VERSION_4_0 && !channel->command) {
>  		/* If not otherwise set, prefetch buffers are used */
>  		if (gsi->version < IPA_VERSION_4_5)
>  			val |= USE_ESCAPE_BUF_ONLY_FMASK;

. . .

> diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
> index 84bb8ae92725..be191993fbec 100644
> --- a/drivers/net/ipa/ipa_main.c
> +++ b/drivers/net/ipa/ipa_main.c

. . .

> @@ -276,6 +276,7 @@ static void ipa_hardware_config_qsb(struct ipa *ipa)
>  
>  	max1 = 12;
>  	switch (version) {
> +	case IPA_VERSION_3_1:

I do this a little differently now.  These values will be
found in the "ipa_data" file for the platform.

Also I think you'd need different values for IPA v3.1 than
for IPA v3.5.1.

>  	case IPA_VERSION_3_5_1:
>  		max0 = 8;
>  		break;
> @@ -404,6 +405,9 @@ static void ipa_hardware_config(struct ipa *ipa)
>  		/* Enable open global clocks (not needed for IPA v4.5) */
>  		val = GLOBAL_FMASK;
>  		val |= GLOBAL_2X_CLK_FMASK;
> +		if (version == IPA_VERSION_3_1)
> +			val |= MISC_FMASK;

I see this being set for a workaround or IPA v3.1 in the
msm-4.4 tree, but the other two flags aren't set in that
case.  So this might not be quite right.

> +
>  		iowrite32(val, ipa->reg_virt + IPA_REG_CLKON_CFG_OFFSET);
>  
>  		/* Disable PA mask to allow HOLB drop */

. . .