From mboxrd@z Thu Jan 1 00:00:00 1970 From: narmstrong@baylibre.com (Neil Armstrong) Date: Wed, 3 Feb 2016 11:24:23 +0100 Subject: [PATCH 2/4] pwm: omap-dmtimer: add sanity checking for load and match values In-Reply-To: <20160201133503.53599493.drivshin.allworx@gmail.com> References: <1454128014-22866-1-git-send-email-drivshin.allworx@gmail.com> <1454128014-22866-3-git-send-email-drivshin.allworx@gmail.com> <20160201133503.53599493.drivshin.allworx@gmail.com> Message-ID: <56B1D557.6040108@baylibre.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/01/2016 07:35 PM, David Rivshin (Allworx) wrote: > On Fri, 29 Jan 2016 23:26:52 -0500 > "David Rivshin (Allworx)" wrote: > >> From: David Rivshin >> >> Add sanity checking to ensure that we do not program load or match >> values that are out of range if a user requests period or duty_cycle >> values which are not achievable. The match value cannot be less than >> the load value (but can be equal), and neither can be 0xffffffff. >> This means that there must be at least one fclk cycle between load >> and match, and another between match and overflow. >> >> Fixes: 6604c6556db9 ("pwm: Add PWM driver for OMAP using dual-mode >> timers") Signed-off-by: David Rivshin >> --- > [...] >> @@ -149,6 +149,24 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, >> period_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, period_ns); >> duty_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, duty_ns); >> >> + if (period_cycles < 2) { >> + dev_info(chip->dev, >> + "period %dns is too short for clock rate %luHz\n", >> + period_ns, clk_rate); >> + goto err_einval; >> + } > [...] > > I had some second thoughts on this over the weekend: > 1) Perhaps the return should be -ERANGE instead of -EINVAL for this case? > 2) Is dev_info() too severe for this? Perhaps dev_dbg() would be better? > Any preferences? > The current management is OK for me. Acked-by: Neil Armstrong Thanks !