linux-kernel - Re: [PATCH v1 4/7] net: ipa: gsi: Use right masks for GSI v1.0 channels hw param

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Message-ID: <476ea450-16d6-6a8f-650b-0a9becbebce5@ieee.org>
Date:   Mon, 1 Mar 2021 20:05:15 -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 4/7] net: ipa: gsi: Use right masks for GSI v1.0
 channels hw param

On 2/11/21 11:50 AM, AngeloGioacchino Del Regno wrote:
> In GSI v1.0 the register GSI_HW_PARAM_2_OFFSET has different layout
> so the number of channels and events per EE are, of course, laid out
> in 8 bits each (0-7, 8-15 respectively).
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
> ---
>  drivers/net/ipa/gsi.c     | 16 +++++++++++++---
>  drivers/net/ipa/gsi_reg.h |  5 +++++
>  2 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
> index b5460cbb085c..3311ffe514c9 100644
> --- a/drivers/net/ipa/gsi.c
> +++ b/drivers/net/ipa/gsi.c
> @@ -1790,7 +1790,7 @@ static void gsi_channel_teardown(struct gsi *gsi)
>  int gsi_setup(struct gsi *gsi)
>  {
>  	struct device *dev = gsi->dev;
> -	u32 val;
> +	u32 val, mask;
>  	int ret;
>  
>  	/* Here is where we first touch the GSI hardware */
> @@ -1804,7 +1804,12 @@ int gsi_setup(struct gsi *gsi)
>  
>  	val = ioread32(gsi->virt + GSI_GSI_HW_PARAM_2_OFFSET);
>  
> -	gsi->channel_count = u32_get_bits(val, NUM_CH_PER_EE_FMASK);
> +	if (gsi->version == IPA_VERSION_3_1)
> +		mask = GSIV1_NUM_CH_PER_EE_FMASK;
> +	else
> +		mask = NUM_CH_PER_EE_FMASK;
> +
> +	gsi->channel_count = u32_get_bits(val, mask);

I have a different way of doing this, at least for
encoding, and I'd rather use a similar convention in
this case.  At some point it might become obvious
that "there's got to be a better way" and I might have
to consider something else, but for now I've been
doing what I describe below.

Anyway, what I'd ask for here is to create a a static
inline function in "ipa_reg.h" (or "gsi_reg.h") to
extract these values.  In this case it might look
like this:

static inline u32 num_ev_per_ee_get(enum ipa_version version,
				    u32 val)
{
        if (version == IPA_VERSION_3_0 || version == IPA_VERSION_3_1)
                return u32_get_bits(val, GENMASK(8, 0));

        return u32_get_bits(val, GENMASK(7, 3));
}

(I'm not sure if the above is correct for all versions...)

Then the caller would do:
	gsi->evt_ring_count = num_ev_per_ee_get(ipa->version, val);

I'd want the same general thing for the channel count.

					-Alex

>  	if (!gsi->channel_count) {
>  		dev_err(dev, "GSI reports zero channels supported\n");
>  		return -EINVAL;
> @@ -1816,7 +1821,12 @@ int gsi_setup(struct gsi *gsi)
>  		gsi->channel_count = GSI_CHANNEL_COUNT_MAX;
>  	}
>  
> -	gsi->evt_ring_count = u32_get_bits(val, NUM_EV_PER_EE_FMASK);
> +	if (gsi->version == IPA_VERSION_3_1)
> +		mask = GSIV1_NUM_EV_PER_EE_FMASK;
> +	else
> +		mask = NUM_EV_PER_EE_FMASK;
> +
> +	gsi->evt_ring_count = u32_get_bits(val, mask);
>  	if (!gsi->evt_ring_count) {
>  		dev_err(dev, "GSI reports zero event rings supported\n");
>  		return -EINVAL;
> diff --git a/drivers/net/ipa/gsi_reg.h b/drivers/net/ipa/gsi_reg.h
> index 0e138bbd8205..4ba579fa21c2 100644
> --- a/drivers/net/ipa/gsi_reg.h
> +++ b/drivers/net/ipa/gsi_reg.h
> @@ -287,6 +287,11 @@ enum gsi_generic_cmd_opcode {
>  			GSI_EE_N_GSI_HW_PARAM_2_OFFSET(GSI_EE_AP)
>  #define GSI_EE_N_GSI_HW_PARAM_2_OFFSET(ee) \
>  			(0x0001f040 + 0x4000 * (ee))
> +
> +/* Fields below are present for IPA v3.1 with GSI version 1 */
> +#define GSIV1_NUM_EV_PER_EE_FMASK	GENMASK(8, 0)
> +#define GSIV1_NUM_CH_PER_EE_FMASK	GENMASK(15, 8)
> +/* Fields below are present for IPA v3.5.1 and above */
>  #define IRAM_SIZE_FMASK			GENMASK(2, 0)
>  #define NUM_CH_PER_EE_FMASK		GENMASK(7, 3)
>  #define NUM_EV_PER_EE_FMASK		GENMASK(12, 8)
>