From abc1c94471450de4fa085f5b1269837f97b1adc5 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 6 Sep 2018 15:49:05 -0700 Subject: soc: qcom: geni: Don't ignore clk_round_rate() errors in geni_se_clk_tbl_get() The function clk_round_rate() is defined to return a "long", not an "unsigned long". That's because it might return a negative error code. Change the call in geni_se_clk_tbl_get() to check for errors. While we're at it, get rid of a useless init of "freq". NOTE: overall the idea that we should iterate over clk_round_rate() to try to reconstruct a table already present in the clock driver is questionable. Specifically: - This method relies on "clk_round_rate()" rounding up. - This method only works if the table is sorted and has no duplicates. ...this patch doesn't try to fix those problems, it just makes the error handling more correct. Fixes: eddac5af0654 ("soc: qcom: Add GENI based QUP Wrapper driver") Signed-off-by: Douglas Anderson Reviewed-by: Matthias Kaehlcke Signed-off-by: Andy Gross --- drivers/soc/qcom/qcom-geni-se.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/soc') diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c index feed3db21c10..1b19b8428c4a 100644 --- a/drivers/soc/qcom/qcom-geni-se.c +++ b/drivers/soc/qcom/qcom-geni-se.c @@ -513,7 +513,7 @@ EXPORT_SYMBOL(geni_se_resources_on); */ int geni_se_clk_tbl_get(struct geni_se *se, unsigned long **tbl) { - unsigned long freq = 0; + long freq = 0; int i; if (se->clk_perf_tbl) { @@ -529,7 +529,7 @@ int geni_se_clk_tbl_get(struct geni_se *se, unsigned long **tbl) for (i = 0; i < MAX_CLK_PERF_LEVEL; i++) { freq = clk_round_rate(se->clk, freq + 1); - if (!freq || freq == se->clk_perf_tbl[i - 1]) + if (freq <= 0 || freq == se->clk_perf_tbl[i - 1]) break; se->clk_perf_tbl[i] = freq; } -- cgit v1.2.3-55-g7522 From 969fc78c37c3fb1363b4669a7d4df9c3804591e7 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 6 Sep 2018 15:49:06 -0700 Subject: soc: qcom: geni: geni_se_clk_freq_match() should always accept multiples The geni_se_clk_freq_match() has some strange semantics. Specifically it is defined with two modes: 1. It can find a clock that's an exact multiple of the requested rate 2. It can find a non-exact match but it can't handle multiples then ...but callers should always be able to handle a clock that is a multiple of the requested clock so mode #2 doesn't really make sense. Let's change the semantics so that the non-exact match can also accept multiples and then change the code to handle that. The only caller of this code is the unlanded SPI driver [1] which currently passes "exact = True", thus it should be safe to change the semantics in this way. ...and, in fact, the SPI driver should likely be modified to pass "exact = False" (with the new semantics) since that will allow it to work with SPI devices that request a clock rate that doesn't exactly match a rate we can make. [1] https://lkml.kernel.org/r/1535107336-2214-1-git-send-email-dkota@codeaurora.org Fixes: eddac5af0654 ("soc: qcom: Add GENI based QUP Wrapper driver") Signed-off-by: Douglas Anderson Reviewed-by: Matthias Kaehlcke Signed-off-by: Andy Gross --- drivers/soc/qcom/qcom-geni-se.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) (limited to 'drivers/soc') diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c index 1b19b8428c4a..ee89ffb6dde8 100644 --- a/drivers/soc/qcom/qcom-geni-se.c +++ b/drivers/soc/qcom/qcom-geni-se.c @@ -544,16 +544,17 @@ EXPORT_SYMBOL(geni_se_clk_tbl_get); * @se: Pointer to the concerned serial engine. * @req_freq: Requested clock frequency. * @index: Index of the resultant frequency in the table. - * @res_freq: Resultant frequency which matches or is closer to the - * requested frequency. + * @res_freq: Resultant frequency of the source clock. * @exact: Flag to indicate exact multiple requirement of the requested * frequency. * - * This function is called by the protocol drivers to determine the matching - * or exact multiple of the requested frequency, as provided by the serial - * engine clock in order to meet the performance requirements. If there is - * no matching or exact multiple of the requested frequency found, then it - * selects the closest floor frequency, if exact flag is not set. + * This function is called by the protocol drivers to determine the best match + * of the requested frequency as provided by the serial engine clock in order + * to meet the performance requirements. + * + * If we return success: + * - if @exact is true then @res_freq / == @req_freq + * - if @exact is false then @res_freq / <= @req_freq * * Return: 0 on success, standard Linux error codes on failure. */ @@ -564,6 +565,9 @@ int geni_se_clk_freq_match(struct geni_se *se, unsigned long req_freq, unsigned long *tbl; int num_clk_levels; int i; + unsigned long best_delta; + unsigned long new_delta; + unsigned int divider; num_clk_levels = geni_se_clk_tbl_get(se, &tbl); if (num_clk_levels < 0) @@ -572,18 +576,21 @@ int geni_se_clk_freq_match(struct geni_se *se, unsigned long req_freq, if (num_clk_levels == 0) return -EINVAL; - *res_freq = 0; + best_delta = ULONG_MAX; for (i = 0; i < num_clk_levels; i++) { - if (!(tbl[i] % req_freq)) { + divider = DIV_ROUND_UP(tbl[i], req_freq); + new_delta = req_freq - tbl[i] / divider; + if (new_delta < best_delta) { + /* We have a new best! */ *index = i; *res_freq = tbl[i]; - return 0; - } - if (!(*res_freq) || ((tbl[i] > *res_freq) && - (tbl[i] < req_freq))) { - *index = i; - *res_freq = tbl[i]; + /* If the new best is exact then we're done */ + if (new_delta == 0) + return 0; + + /* Record how close we got */ + best_delta = new_delta; } } -- cgit v1.2.3-55-g7522