| Message ID | 1345608318-15347-1-git-send-email-dianders@chromium.org (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
Hi Doug, I didn't know what purpose is. Why need to add the MMC_CAP2_NO_MMC? If card is SD or SDIO, mmc_attach_mmc(host) should not be entered. Could you explain to me in more detail? Best Regards, Jaehoon Chung On 08/22/2012 01:05 PM, Doug Anderson wrote: > On some systems we need a way to disable MMC card support in a MMC/SD > card slot. Add support in the core SD/MMC code to support this. > > Signed-off-by: Doug Anderson <dianders@chromium.org> > Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com> > --- > drivers/mmc/core/core.c | 2 +- > include/linux/mmc/host.h | 1 + > 2 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 8ac5246..3214972 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -1981,7 +1981,7 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq) > return 0; > if (!mmc_attach_sd(host)) > return 0; > - if (!mmc_attach_mmc(host)) > + if (!(host->caps2 & MMC_CAP2_NO_MMC) && !mmc_attach_mmc(host)) > return 0; > > mmc_power_off(host); > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index f578a71..f36370e 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -257,6 +257,7 @@ struct mmc_host { > #define MMC_CAP2_HC_ERASE_SZ (1 << 9) /* High-capacity erase size */ > #define MMC_CAP2_CD_ACTIVE_HIGH (1 << 10) /* Card-detect signal active high */ > #define MMC_CAP2_RO_ACTIVE_HIGH (1 << 11) /* Write-protect signal active high */ > +#define MMC_CAP2_NO_MMC (1 << 12) /* Only SD supported, not MMC */ > > mmc_pm_flag_t pm_caps; /* supported pm features */ > unsigned int power_notify_type; > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Jaehoon, On Tue, Aug 21, 2012 at 9:35 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote: > > Hi Doug, > > I didn't know what purpose is. > Why need to add the MMC_CAP2_NO_MMC? > If card is SD or SDIO, mmc_attach_mmc(host) should not be entered. > Could you explain to me in more detail? Thanks for your feedback. In this case I have a card that is an MMC card so mmc_attach_sdio() and mmc_attach_sd() will fail. If I let mmc_attach_mmc() run it will actually find the MMC card. However, on this platform it is not valid to recognize MMC cards. -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Aug 22, 2012, at 8:44 AM, Doug Anderson <dianders@chromium.org> wrote: > Jaehoon, > > On Tue, Aug 21, 2012 at 9:35 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote: >> >> Hi Doug, >> >> I didn't know what purpose is. >> Why need to add the MMC_CAP2_NO_MMC? >> If card is SD or SDIO, mmc_attach_mmc(host) should not be entered. >> Could you explain to me in more detail? > > Thanks for your feedback. In this case I have a card that is an MMC > card so mmc_attach_sdio() and mmc_attach_sd() will fail. If I let > mmc_attach_mmc() run it will actually find the MMC card. However, on > this platform it is not valid to recognize MMC cards. > Understand. Can you explain why the change is needed. Is it for technical reasons that MMC is not allowed -- if so then I do not understand how SD can work and MMC cannot. If it is for marketing reasons -- then --- oh well ..... Could you add some additional comments to the commit message. I think it makes sense to handle all 3 cases a) SDIO not allowed b) SD not allowed c) MMC not allowed > -Doug > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Wed, Aug 22, 2012 at 9:00 AM, Philip Rakity <prakity@marvell.com> wrote: > > On Aug 22, 2012, at 8:44 AM, Doug Anderson <dianders@chromium.org> wrote: > >> Jaehoon, >> >> On Tue, Aug 21, 2012 at 9:35 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote: >>> >>> Hi Doug, >>> >>> I didn't know what purpose is. >>> Why need to add the MMC_CAP2_NO_MMC? >>> If card is SD or SDIO, mmc_attach_mmc(host) should not be entered. >>> Could you explain to me in more detail? >> >> Thanks for your feedback. In this case I have a card that is an MMC >> card so mmc_attach_sdio() and mmc_attach_sd() will fail. If I let >> mmc_attach_mmc() run it will actually find the MMC card. However, on >> this platform it is not valid to recognize MMC cards. >> > > > Understand. > > Can you explain why the change is needed. Is it for technical > reasons that MMC is not allowed -- if so then I do not understand how SD can work > and MMC cannot. > > If it is for marketing reasons -- then --- oh well ..... > > > Could you add some additional comments to the commit message. > I think it makes sense to handle all 3 cases > a) SDIO not allowed > b) SD not allowed > c) MMC not allowed We are working with a system manufacturer who wishes to only support SD cards in their product, and need to accommodate that. It made sense for us to contribute this work upstream since others might want to do the same in the future for some reason. Adding all three cases makes sense if others foresee a use case for it. -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 22 Aug 2012, Olof Johansson wrote: > On Wed, Aug 22, 2012 at 9:00 AM, Philip Rakity <prakity@marvell.com> wrote: > > > > On Aug 22, 2012, at 8:44 AM, Doug Anderson <dianders@chromium.org> wrote: > > > >> Thanks for your feedback. In this case I have a card that is an MMC > >> card so mmc_attach_sdio() and mmc_attach_sd() will fail. If I let > >> mmc_attach_mmc() run it will actually find the MMC card. However, on > >> this platform it is not valid to recognize MMC cards. > >> > > > > > > Understand. > > > > Can you explain why the change is needed. Is it for technical > > reasons that MMC is not allowed -- if so then I do not understand how SD can work > > and MMC cannot. > > > > If it is for marketing reasons -- then --- oh well ..... > > > > > > Could you add some additional comments to the commit message. > > I think it makes sense to handle all 3 cases > > a) SDIO not allowed > > b) SD not allowed > > c) MMC not allowed > > We are working with a system manufacturer who wishes to only support > SD cards in their product, and need to accommodate that. It made sense > for us to contribute this work upstream since others might want to do > the same in the future for some reason. > > Adding all three cases makes sense if others foresee a use case for it. Isn't this rather revolting? Personally I find such "feature" totally ridiculous. If said manufacturer doesn't want to support MMC cards, they just have to not advertise it, period. Or if they really mean it, then they only have to state it explicitly in their user manual, and repeat it if ever problems are reported. Dumbing down kernel functionality to serve marketing purpose or technology lock-ins is utterly stupid. Purposely restricting interoperability might even be ruled illegal in some jurisdictions. I therefore insist on providing a vehement NAK on such patches. Nicolas -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Aug 22, 2012 at 11:25 AM, Nicolas Pitre <nico@fluxnic.net> wrote: > On Wed, 22 Aug 2012, Olof Johansson wrote: > >> On Wed, Aug 22, 2012 at 9:00 AM, Philip Rakity <prakity@marvell.com> wrote: >> > >> > On Aug 22, 2012, at 8:44 AM, Doug Anderson <dianders@chromium.org> wrote: >> > >> >> Thanks for your feedback. In this case I have a card that is an MMC >> >> card so mmc_attach_sdio() and mmc_attach_sd() will fail. If I let >> >> mmc_attach_mmc() run it will actually find the MMC card. However, on >> >> this platform it is not valid to recognize MMC cards. >> >> >> > >> > >> > Understand. >> > >> > Can you explain why the change is needed. Is it for technical >> > reasons that MMC is not allowed -- if so then I do not understand how SD can work >> > and MMC cannot. >> > >> > If it is for marketing reasons -- then --- oh well ..... >> > >> > >> > Could you add some additional comments to the commit message. >> > I think it makes sense to handle all 3 cases >> > a) SDIO not allowed >> > b) SD not allowed >> > c) MMC not allowed >> >> We are working with a system manufacturer who wishes to only support >> SD cards in their product, and need to accommodate that. It made sense >> for us to contribute this work upstream since others might want to do >> the same in the future for some reason. >> >> Adding all three cases makes sense if others foresee a use case for it. > > Isn't this rather revolting? > > Personally I find such "feature" totally ridiculous. If said > manufacturer doesn't want to support MMC cards, they just have to not > advertise it, period. Or if they really mean it, then they only have to > state it explicitly in their user manual, and repeat it if ever problems > are reported. > > Dumbing down kernel functionality to serve marketing purpose or > technology lock-ins is utterly stupid. Purposely restricting > interoperability might even be ruled illegal in some jurisdictions. > > I therefore insist on providing a vehement NAK on such patches. Ok, thanks. We'll keep carrying it locally instead then. -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 8ac5246..3214972 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1981,7 +1981,7 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq) return 0; if (!mmc_attach_sd(host)) return 0; - if (!mmc_attach_mmc(host)) + if (!(host->caps2 & MMC_CAP2_NO_MMC) && !mmc_attach_mmc(host)) return 0; mmc_power_off(host); diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index f578a71..f36370e 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -257,6 +257,7 @@ struct mmc_host { #define MMC_CAP2_HC_ERASE_SZ (1 << 9) /* High-capacity erase size */ #define MMC_CAP2_CD_ACTIVE_HIGH (1 << 10) /* Card-detect signal active high */ #define MMC_CAP2_RO_ACTIVE_HIGH (1 << 11) /* Write-protect signal active high */ +#define MMC_CAP2_NO_MMC (1 << 12) /* Only SD supported, not MMC */ mmc_pm_flag_t pm_caps; /* supported pm features */ unsigned int power_notify_type;