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Message-ID: <399e3fda-91c0-6dcb-5040-a117fe78519d@amlogic.com>
Date: Thu, 7 Nov 2019 03:07:13 +0000
From: Nan Li <Nan.Li@...ogic.com>
To: Jerome Brunet <jbrunet@...libre.com>,
Jianxin Pan <Jianxin.Pan@...ogic.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Kevin Hilman <khilman@...libre.com>
CC: Neil Armstrong <narmstrong@...libre.com>,
"linux-amlogic@...ts.infradead.org"
<linux-amlogic@...ts.infradead.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Victor Wan <victor.wan@...ogic.com>
Subject: Re: [PATCH v2] mmc: meson-gx: fix mmc dma operation
On 2019/11/5 21:30, Jerome Brunet wrote:
>
> On Tue 05 Nov 2019 at 10:05, Nan Li <Nan.Li@...ogic.com> wrote:
>
> Nan Li, please fix your mailer to use plain text properly, your reply
> are near impossible to read
>
Sorry, maybe there is something wrong with my email address. Please help
me check whether my reply is in accordance with the format.
>> 在 2019/11/5 16:54, Jerome Brunet 写道:
>>
>>
>> On Tue 05 Nov 2019 at 09:30, Nan Li <Nan.Li@...ogic.com><mailto:Nan.Li@...ogic.com> wrote:
>>
>>
>>
>>
>>
>> Based on Uffe comment I tried something else.
>>
>> Basically, it enables chained mode in the driver only when the framework
>> calls pre/post_req callback. As far as understood, the framework calls
>> this when there is more than one request pending ... which seems to be
>> when chained mode actually make sense
>>
>> Jerome, what you are talking about is the system framework problem when you call pre/post_req,
>>
>> which is not related to the patch I submitted.
>>
>>
>>
>> I strongly disagree.
>> As far as I understand from your description, the problem was with the
>> life cycle of the dma mapping. This is tighly related with pre/post req.
>> Just the variable names you have picked clearly show that.
>>
>>
>>
>> As you said, pre/post_req is called only when there is data to implement the chained mode,
>>
>> but it is also possible to cause memory consistency problems,
>> resulting in incorrect data.
>>
>>
>>
>> The life cycle of the mapping is also taken care of with patch,
>> since dma mapping is no longer handled in .request(). IOW the mapping,
>> if any, will be released after the request is done using .post_req()
>>
>> If you think otherwise, please elaborate.
>>
>>
>> I see what you mean. You want to pull the pre/post_req operation out of the request interface and invoke it at the top.
>>
>> I didn't notice the following modification of patch in your last email and reply in time. I'm really sorry.
>>
>> The following patch removes all pre/post_req operations,
>>
>>
>>
>> No it does not. Callbacks are still provided to the MMC framework.
>>
>>
>>
>> but you do not send out the operation patch added to the upper layer
>> together.
>>
>>
>>
>> There is no modification needed in the upper layer
>>
>>
>>
>>
>> Then the patch is incomplete, which will affect the dma data transfer function in start_cmd function and affect the multi-block write operation.
>>
>>
>>
>>
>> No it is not incomplete. pre and post request are correctly called. You
>> can check that with ftrace if you want.
>>
>> Maybe you could try it ?
>>
>>
>> I'm sorry, I didn't catch your meaning.How do I use pre/post_req
>> properly?
>
> Those callbacks are provided to the framework as well. If you have
> trouble following, please apply the patch and look at the driver
>
> Have a look at "meson_mmc_ops"
>
>>
>> Do you mean I need to add a call to pre/post_req on top of the changes
>> you provided below?
>
> No, you should not
>
>>
>> If not, your changes have deleted all pre/post_req calls.
>
> No, it does not. It relies on the framework to activate the chained mode
> or not. Again, if you have trouble following you can try to enable
> ftrace and trace the mmc functions.
>
>>
>>
>>
>>
>> Please send your complete patch, including core layer modification,
>> thank you.
>>
>>
>>
>>
>>
>> Therefore, this patch is added to make memory consistent and obtain real effective information.
>>
>>
>>
>> ----8<-----
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index e712315c7e8d..399604b4124d 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -126,8 +126,7 @@
>> #define SD_EMMC_CFG_CMD_GAP 16 /* in clock cycles */
>> #define SD_EMMC_DESC_BUF_LEN PAGE_SIZE
>>
>> -#define SD_EMMC_PRE_REQ_DONE BIT(0)
>> -#define SD_EMMC_DESC_CHAIN_MODE BIT(1)
>> +#define SD_EMMC_DESC_CHAIN_MODE BIT(0)
>>
>> #define MUX_CLK_NUM_PARENTS 2
>>
>> @@ -228,7 +227,6 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
>> struct mmc_data *data = mrq->data;
>> struct scatterlist *sg;
>> int i;
>> - bool use_desc_chain_mode = true;
>>
>> /*
>> * When Controller DMA cannot directly access DDR memory, disable
>> @@ -251,12 +249,11 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
>> /* check for 8 byte alignment */
>> if (sg->offset & 7) {
>> WARN_ONCE(1, "unaligned scatterlist buffer\n");
>> - use_desc_chain_mode = false;
>> - break;
>> + return;
>> }
>>
>> - if (use_desc_chain_mode)
>> - data->host_cookie |= SD_EMMC_DESC_CHAIN_MODE;
>> + /* The planets are aligned, let's chain them up */
>> + data->host_cookie |= SD_EMMC_DESC_CHAIN_MODE;
>> }
>>
>> static inline bool meson_mmc_desc_chain_mode(const struct mmc_data *data)
>> @@ -278,7 +275,6 @@ static void meson_mmc_pre_req(struct mmc_host *mmc, struct mmc_request *mrq)
>> return;
>>
>> meson_mmc_get_transfer_mode(mmc, mrq);
>> - data->host_cookie |= SD_EMMC_PRE_REQ_DONE;
>>
>> if (!meson_mmc_desc_chain_mode(data))
>> return;
>> @@ -803,25 +799,11 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
>> static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
>> {
>> struct meson_host *host = mmc_priv(mmc);
>> - bool needs_pre_post_req = mrq->data &&
>> - !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);
>> -
>> - if (needs_pre_post_req) {
>> - meson_mmc_get_transfer_mode(mmc, mrq);
>> - if (!meson_mmc_desc_chain_mode(mrq->data))
>> - needs_pre_post_req = false;
>> - }
>> -
>> - if (needs_pre_post_req)
>> - meson_mmc_pre_req(mmc, mrq);
>>
>> /* Stop execution */
>> writel(0, host->regs + SD_EMMC_START);
>>
>> meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
>> -
>> - if (needs_pre_post_req)
>> - meson_mmc_post_req(mmc, mrq, 0);
>> }
>>
>> static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
>> ---->8-----
>>
>> No performance hit AFAICT.
>> From your description, it should address your problem too.
>>
>>
>>
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index e712315..7667e8a 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -173,6 +173,7 @@ struct meson_host {
>> int irq;
>>
>> bool vqmmc_enabled;
>> + bool needs_pre_post_req;
>> };
>>
>> #define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
>> @@ -654,6 +655,8 @@ static void meson_mmc_request_done(struct mmc_host *mmc,
>> struct meson_host *host = mmc_priv(mmc);
>>
>> host->cmd = NULL;
>> + if (host->needs_pre_post_req)
>> + meson_mmc_post_req(mmc, mrq, 0);
>> mmc_request_done(host->mmc, mrq);
>> }
>>
>> @@ -803,25 +806,23 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
>> static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
>> {
>> struct meson_host *host = mmc_priv(mmc);
>> - bool needs_pre_post_req = mrq->data &&
>> +
>> + host->needs_pre_post_req = mrq->data &&
>> !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);
>>
>> - if (needs_pre_post_req) {
>> + if (host->needs_pre_post_req) {
>> meson_mmc_get_transfer_mode(mmc, mrq);
>> if (!meson_mmc_desc_chain_mode(mrq->data))
>> - needs_pre_post_req = false;
>> + host->needs_pre_post_req = false;
>> }
>>
>> - if (needs_pre_post_req)
>> + if (host->needs_pre_post_req)
>> meson_mmc_pre_req(mmc, mrq);
>>
>> /* Stop execution */
>> writel(0, host->regs + SD_EMMC_START);
>>
>> meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
>> -
>> - if (needs_pre_post_req)
>> - meson_mmc_post_req(mmc, mrq, 0);
>> }
>>
>> static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
>
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