linux-kernel - Re: [PATCH net-next v2 2/4] net: ipa: use upper_32

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Message-ID: <75a8c09b-783a-6d05-2e56-02bd02ff3ff0@gmail.com>
Date:   Thu, 18 Mar 2021 09:03:32 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Alex Elder <elder@...aro.org>, davem@...emloft.net, kuba@...nel.org
Cc:     bjorn.andersson@...aro.org, evgreen@...omium.org,
        cpratapa@...eaurora.org, subashab@...eaurora.org, elder@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/4] net: ipa: use upper_32_bits()



On 3/18/2021 6:51 AM, Alex Elder wrote:
> Use upper_32_bits() to extract the high-order 32 bits of a DMA
> address.  This avoids doing a 32-position shift on a DMA address
> if it happens not to be 64 bits wide.
> 
> Suggested-by: Florian Fainelli <f.fainelli@...il.com>
> Signed-off-by: Alex Elder <elder@...aro.org>
> ---
> v2: - Switched to use the existing function, as suggested by Florian.
> 
>  drivers/net/ipa/gsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
> index 2119367b93ea9..82c5a0d431ee5 100644
> --- a/drivers/net/ipa/gsi.c
> +++ b/drivers/net/ipa/gsi.c
> @@ -711,7 +711,7 @@ static void gsi_evt_ring_program(struct gsi *gsi, u32 evt_ring_id)
>  	val = evt_ring->ring.addr & GENMASK(31, 0);

Did you want to introduce another patch to use lower_32_bits() for the
assignment above?

>  	iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_2_OFFSET(evt_ring_id));
>  
> -	val = evt_ring->ring.addr >> 32;
> +	val = upper_32_bits(evt_ring->ring.addr);
>  	iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_3_OFFSET(evt_ring_id));
>  
>  	/* Enable interrupt moderation by setting the moderation delay */
> @@ -819,7 +819,7 @@ static void gsi_channel_program(struct gsi_channel *channel, bool doorbell)
>  	val = channel->tre_ring.addr & GENMASK(31, 0);

And likewise?

>  	iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_2_OFFSET(channel_id));
>  
> -	val = channel->tre_ring.addr >> 32;
> +	val = upper_32_bits(channel->tre_ring.addr);
>  	iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_3_OFFSET(channel_id));
>  
>  	/* Command channel gets low weighted round-robin priority */
> 

-- 
Florian