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SubjectRe: [PATCH net v3] net: macb: Correct usage of MACB_CAPS_CLK_HW_CHG flag
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Hi Charles,

On 04.01.2021 12:38, Charles Keepax wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> A new flag MACB_CAPS_CLK_HW_CHG was added and all callers of
> macb_set_tx_clk were gated on the presence of this flag.
>
> - if (!clk)
> + if (!bp->tx_clk || !(bp->caps & MACB_CAPS_CLK_HW_CHG))
>
> However the flag was not added to anything other than the new
> sama7g5_gem, turning that function call into a no op for all other
> systems. This breaks the networking on Zynq.
>
> The commit message adding this states: a new capability so that
> macb_set_tx_clock() to not be called for IPs having this
> capability
>
> This strongly implies that present of the flag was intended to skip
> the function not absence of the flag. Update the if statement to
> this effect, which repairs the existing users.

Yes, the presence of the flag should involve skipping the calling of
clk_set_rate() since the IP logic would take care of proper clock division
depending on the link speed. I wrongly cherry pick this one from internal
branches. Sorry for this breakage.

>
> Fixes: daafa1d33cc9 ("net: macb: add capability to not set the clock rate")
> Suggested-by: Andrew Lunn <andrew@lunn.ch>
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>

> ---
>
> Changes since v1:
> - Updated flag semantics to skip function, as appears to have been
> intended by the initial commit.
>
> Changes since v2:
> - Adding "net" to the subject line
>
> Thanks,
> Charles
>
> drivers/net/ethernet/cadence/macb_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index d5d910916c2e8..814a5b10141d1 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -467,7 +467,7 @@ static void macb_set_tx_clk(struct macb *bp, int speed)
> {
> long ferr, rate, rate_rounded;
>
> - if (!bp->tx_clk || !(bp->caps & MACB_CAPS_CLK_HW_CHG))
> + if (!bp->tx_clk || (bp->caps & MACB_CAPS_CLK_HW_CHG))
> return;
>
> switch (speed) {
> --
> 2.11.0
>
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